1
|
Gievers M, Wagner M, Schmidt R. Probing Polaron Clouds by Rydberg Atom Spectroscopy. PHYSICAL REVIEW LETTERS 2024; 132:053401. [PMID: 38364123 DOI: 10.1103/physrevlett.132.053401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Revised: 10/24/2023] [Accepted: 12/06/2023] [Indexed: 02/18/2024]
Abstract
In recent years, Rydberg excitations in atomic quantum gases have become a successful platform to explore quantum impurity problems. A single impurity immersed in a Fermi gas leads to the formation of a polaron, a quasiparticle consisting of the impurity being dressed by the surrounding medium. With a radius of about the Fermi wavelength, the density profile of a polaron cannot be explored using in situ optical imaging techniques. In this Letter, we propose a new experimental measurement technique that enables the in situ imaging of the polaron cloud in ultracold quantum gases. The impurity atom induces the formation of a polaron cloud and is then excited to a Rydberg state. Because of the mesoscopic interaction range of Rydberg excitations, which can be tuned by the principal numbers of the Rydberg state, atoms extracted from the polaron cloud form dimers with the impurity. By performing first principle calculations of the absorption spectrum based on a functional determinant approach, we show how the occupation of the dimer state can be directly observed in spectroscopy experiments and can be mapped onto the density profile of the gas particles, hence providing a direct, real-time, and in situ measure of the polaron cloud.
Collapse
Affiliation(s)
- Marcel Gievers
- Arnold Sommerfeld Center for Theoretical Physics, Center for NanoScience, and Munich Center for Quantum Science and Technology, Ludwig-Maximilians-Universität München, 80333 Munich, Germany
- Max Planck Institute of Quantum Optics, 85748 Garching, Germany
| | - Marcel Wagner
- Institut für Theoretische Physik, Universität Heidelberg, 69120 Heidelberg, Germany
| | - Richard Schmidt
- Institut für Theoretische Physik, Universität Heidelberg, 69120 Heidelberg, Germany
| |
Collapse
|
2
|
Shen X, Davidson N, Bruun GM, Sun M, Wu Z. Strongly Interacting Bose-Fermi Mixtures: Mediated Interaction, Phase Diagram, and Sound Propagation. PHYSICAL REVIEW LETTERS 2024; 132:033401. [PMID: 38307087 DOI: 10.1103/physrevlett.132.033401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/14/2023] [Accepted: 12/06/2023] [Indexed: 02/04/2024]
Abstract
Motivated by recent surprising experimental findings, we develop a strong-coupling theory for Bose-Fermi mixtures capable of treating resonant interspecies interactions while satisfying the compressibility sum rule. We show that the mixture can be stable at large interaction strengths close to resonance, in agreement with the experiment, but at odds with the widely used perturbation theory. We also calculate the sound velocity of the Bose gas in the ^{133}Cs-^{6}Li mixture, again finding good agreement with the experimental observations both at weak and strong interactions. A central ingredient of our theory is the generalization of a fermion mediated interaction to strong Bose-Fermi scatterings and to finite frequencies. This further leads to a predicted hybridization of the sound modes of the Bose and Fermi gases, which can be directly observed using Bragg spectroscopy.
Collapse
Affiliation(s)
- Xin Shen
- College of Sciences, China Jiliang University, Hangzhou 310018, China
| | - Nir Davidson
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Georg M Bruun
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Aarhus C, Denmark
| | - Mingyuan Sun
- State Key Lab of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
- School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Zhigang Wu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Physics, The University of Hong Kong, Hong Kong, China
| |
Collapse
|
3
|
Petković A, Ristivojevic Z. Dissipative Dynamics of a Heavy Impurity in a Bose Gas in the Strong Coupling Regime. PHYSICAL REVIEW LETTERS 2023; 131:186001. [PMID: 37977626 DOI: 10.1103/physrevlett.131.186001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 06/26/2023] [Accepted: 09/29/2023] [Indexed: 11/19/2023]
Abstract
We study the motion of a heavy impurity in a one-dimensional Bose gas. The impurity experiences the friction force due to scattering off thermally excited quasiparticles. We present detailed analysis of an arbitrarily strong impurity-boson coupling in a wide range of temperatures within a microscopic theory. Focusing mostly on weakly interacting bosons, we derive an analytical result for the friction force and uncover new regimes of the impurity dynamics. Particularly interesting is the low-temperature T^{2} dependence of the friction force obtained for a strongly coupled impurity, which should be contrasted with the expected T^{4} scaling. This new regime applies to systems of bosons with an arbitrary repulsion strength. We finally study the evolution of the impurity with a given initial momentum. We evaluate analytically its nonstationary momentum distribution function. The impurity relaxation towards the equilibrium is a realization of the Ornstein-Uhlenbeck process in momentum space.
Collapse
Affiliation(s)
- Aleksandra Petković
- Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, 31062 Toulouse, France
| | - Zoran Ristivojevic
- Laboratoire de Physique Théorique, Université de Toulouse, CNRS, UPS, 31062 Toulouse, France
| |
Collapse
|
4
|
Colussi VE, Caleffi F, Menotti C, Recati A. Lattice Polarons across the Superfluid to Mott Insulator Transition. PHYSICAL REVIEW LETTERS 2023; 130:173002. [PMID: 37172254 DOI: 10.1103/physrevlett.130.173002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 01/11/2023] [Accepted: 03/17/2023] [Indexed: 05/14/2023]
Abstract
We study the physics of a mobile impurity confined in a two-dimensional lattice, moving within a Bose-Hubbard bath at zero temperature. Exploiting the quantum Gutzwiller formalism, we develop a beyond-Fröhlich model of the bath-impurity interaction to describe the properties of the polaronic quasiparticle formed by the dressing of the impurity by quantum fluctuations of the bath. We find a stable and well-defined polaron throughout the entire phase diagram of the bath, except for the very low tunneling limit of the hard-core superfluid. The polaron properties are highly sensitive to the different universality classes of the quantum phase transition between the superfluid and Mott insulating phases, providing an unambiguous probe of correlations and collective modes in a quantum critical many-body environment.
Collapse
Affiliation(s)
- V E Colussi
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, I-38123 Trento, Italy
| | - F Caleffi
- International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy
| | - C Menotti
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, I-38123 Trento, Italy
| | - A Recati
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, I-38123 Trento, Italy
- Trento Institute for Fundamental Physics and Applications, INFN, Via Sommarive 14, 38123 Povo, Trento, Italy
| |
Collapse
|
5
|
Cayla H, Massignan P, Giamarchi T, Aspect A, Westbrook CI, Clément D. Observation of 1/k^{4}-Tails after Expansion of Bose-Einstein Condensates with Impurities. PHYSICAL REVIEW LETTERS 2023; 130:153401. [PMID: 37115901 DOI: 10.1103/physrevlett.130.153401] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 03/17/2023] [Indexed: 06/19/2023]
Abstract
We measure the momentum density in a Bose-Einstein condensate (BEC) with dilute spin impurities after an expansion in the presence of interactions. We observe tails decaying as 1/k^{4} at large momentum k in the condensate and in the impurity cloud. These algebraic tails originate from the impurity-BEC interaction, but their amplitudes greatly exceed those expected from two-body contact interactions at equilibrium in the trap. Furthermore, in the absence of impurities, such algebraic tails are not found in the BEC density measured after the interaction-driven expansion. These results highlight the key role played by impurities when present, a possibility that had not been considered in our previous work [Chang et al., Phys. Rev. Lett. 117, 235303 (2016)PRLTAO0031-900710.1103/PhysRevLett.117.235303]. Our measurements suggest that these unexpected algebraic tails originate from the nontrivial dynamics of the expansion in the presence of impurity-bath interactions.
Collapse
Affiliation(s)
- Hugo Cayla
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127, Palaiseau, France
| | - Pietro Massignan
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona, Spain
| | - Thierry Giamarchi
- Department of Quantum Matter Physics, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva, Switzerland
| | - Alain Aspect
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127, Palaiseau, France
| | - Christoph I Westbrook
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127, Palaiseau, France
| | - David Clément
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127, Palaiseau, France
| |
Collapse
|
6
|
Strongly Interacting Bose Polarons in Two-Dimensional Atomic Gases and Quantum Fluids of Polaritons. ATOMS 2022. [DOI: 10.3390/atoms11010003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Polarons are quasiparticles relevant across many fields in physics: from condensed matter to atomic physics. Here, we study the quasiparticle properties of two-dimensional strongly interacting Bose polarons in atomic Bose–Einstein condensates and polariton gases. Our studies are based on the non-self consistent T-matrix approximation adapted to these physical systems. For the atomic case, we study the spectral and quasiparticle properties of the polaron in the presence of a magnetic Feshbach resonance. We show the presence of two polaron branches: an attractive polaron, a low-lying state that appears as a well-defined quasiparticle for weak attractive interactions, and a repulsive polaron, a metastable state that becomes the dominant branch at weak repulsive interactions. In addition, we study a polaron arising from the dressing of a single itinerant electron by a quantum fluid of polaritons in a semiconductor microcavity. We demonstrate the persistence of the two polaron branches whose properties can be controlled over a wide range of parameters by tuning the cavity mode.
Collapse
|
7
|
Jia C, Liang Z. Interaction between an Impurity and Nonlinear Excitations in a Polariton Condensate. ENTROPY (BASEL, SWITZERLAND) 2022; 24:1789. [PMID: 36554194 PMCID: PMC9778002 DOI: 10.3390/e24121789] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Revised: 11/29/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
Exploring the dynamics of a mobile impurity immersed in field excitations is challenging, as it requires to account for the entanglement between the impurity and the surrounding excitations. To this end, the impurity's effective mass has to be considered as finite, rather than infinite. Here, we theoretically investigate the interaction between a finite-mass impurity and a dissipative soliton representing nonlinear excitations in the polariton Bose-Einstein condensate (BEC). Using the Lagrange variational method and the open-dissipative Gross-Pitaevskii equation, we analytically derive the interaction phase diagram between the impurity and a dissipative bright soliton in the polariton BEC. Depending on the impurity mass, we find the dissipative soliton colliding with the impurity can transmit through, get trapped, or be reflected. This work opens a new perspective in understanding the impurity dynamics when immersed in field excitations, as well as potential applications in information processing with polariton solitons.
Collapse
|
8
|
Fujii K, Hongo M, Enss T. Universal van der Waals Force between Heavy Polarons in Superfluids. PHYSICAL REVIEW LETTERS 2022; 129:233401. [PMID: 36563199 DOI: 10.1103/physrevlett.129.233401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2022] [Revised: 09/22/2022] [Accepted: 11/02/2022] [Indexed: 06/17/2023]
Abstract
We investigate the long-range behavior of the induced Casimir interaction between two spinless heavy impurities, or polarons, in superfluid cold atomic gases. With the help of effective field theory (EFT) of a Galilean invariant superfluid, we show that the induced impurity-impurity potential at long distance universally shows a relativistic van der Waals-like attraction (∼1/r^{7}) resulting from the exchange of two superfluid phonons. We also clarify finite temperature effects from the same two-phonon exchange process. The temperature T introduces the additional length scale c_{s}/T with the speed of sound c_{s}. Leading corrections at finite temperature scale as T^{6}/r for distances r≪c_{s}/T smaller than the thermal length. For larger distances the potential shows a nonrelativistic van der Waals behavior (∼T/r^{6}) instead of the relativistic one. Our EFT formulation applies not only to weakly coupled Bose or Fermi superfluids but also to those composed of strongly correlated unitary fermions with a weakly coupled impurity. The sound velocity controls the magnitude of the van der Waals potential, which we evaluate for the fermionic superfluid in the BCS-BEC crossover.
Collapse
Affiliation(s)
- Keisuke Fujii
- Institut für Theoretische Physik, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - Masaru Hongo
- Department of Physics, Niigata University, Niigata 950-2181, Japan
- RIKEN iTHEMS, RIKEN, Wako 351-0198, Japan
| | - Tilman Enss
- Institut für Theoretische Physik, Universität Heidelberg, D-69120 Heidelberg, Germany
| |
Collapse
|
9
|
Ding S, Drewsen M, Arlt JJ, Bruun GM. Mediated Interaction between Ions in Quantum Degenerate Gases. PHYSICAL REVIEW LETTERS 2022; 129:153401. [PMID: 36269954 DOI: 10.1103/physrevlett.129.153401] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2022] [Revised: 08/04/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
We explore the interaction between two trapped ions mediated by a surrounding quantum degenerate Bose or Fermi gas. Using perturbation theory valid for weak atom-ion interaction, we show analytically that the interaction mediated by a Bose gas has a power-law behavior for large distances whereas it has a Yukawa form for intermediate distances. For a Fermi gas, the mediated interaction is given by a power law for large density and by a Ruderman-Kittel-Kasuya-Yosida form for low density. For strong atom-ion interaction, we use a diagrammatic theory to demonstrate that the mediated interaction can be a significant addition to the bare Coulomb interaction between the ions, when an atom-ion bound state is close to threshold. Finally, we show that the induced interaction leads to substantial and observable shifts in the ion phonon frequencies.
Collapse
Affiliation(s)
- Shanshan Ding
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Aarhus C, Denmark
| | - Michael Drewsen
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Aarhus C, Denmark
| | - Jan J Arlt
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Aarhus C, Denmark
| | - G M Bruun
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Aarhus C, Denmark
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
10
|
Su Z, Yang H, Cao J, Wang XY, Rui J, Zhao B, Pan JW. Resonant Control of Elastic Collisions between ^{23}Na^{40}K Molecules and ^{40}K Atoms. PHYSICAL REVIEW LETTERS 2022; 129:033401. [PMID: 35905340 DOI: 10.1103/physrevlett.129.033401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/24/2022] [Accepted: 07/01/2022] [Indexed: 06/15/2023]
Abstract
We have demonstrated the resonant control of the elastic scattering cross sections in the vicinity of Feshbach resonances between ^{23}Na^{40}K molecules and ^{40}K atoms by studying the thermalization between them. The elastic scattering cross sections vary by more than 2 orders of magnitude close to the resonance, and can be well described by an asymmetric Fano profile. The parameters that characterize the magnetically tunable s-wave scattering length are determined from the elastic scattering cross sections. The observation of resonantly controlled elastic scattering cross sections opens up the possibility to study strongly interacting atom-molecule mixtures and improve our understanding of the complex atom-molecule Feshbach resonances.
Collapse
Affiliation(s)
- Zhen Su
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Huan Yang
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Jin Cao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Xin-Yao Wang
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Jun Rui
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Bo Zhao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Jian-Wei Pan
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| |
Collapse
|
11
|
Abstract
Polaron quasiparticles are formed when a mobile impurity is coupled to the elementary excitations of a many-particle background. In the field of ultracold atoms, the study of the associated impurity problem has attracted a growing interest over the last fifteen years. Polaron quasiparticle properties are essential to our understanding of a variety of paradigmatic quantum many-body systems realized in ultracold atomic gases and in the solid state, from imbalanced Bose–Fermi and Fermi–Fermi mixtures to fermionic Hubbard models. In this topical review, we focus on the so-called repulsive polaron branch, which emerges as an excited many-body state in systems with underlying attractive interactions such as ultracold atomic mixtures, and is characterized by an effective repulsion between the impurity and the surrounding medium. We give a brief account of the current theoretical and experimental understanding of repulsive polaron properties, for impurities embedded in both fermionic and bosonic media, and we highlight open issues deserving future investigations.
Collapse
|
12
|
Christianen A, Cirac JI, Schmidt R. Chemistry of a Light Impurity in a Bose-Einstein Condensate. PHYSICAL REVIEW LETTERS 2022; 128:183401. [PMID: 35594082 DOI: 10.1103/physrevlett.128.183401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Revised: 03/30/2022] [Accepted: 04/04/2022] [Indexed: 06/15/2023]
Abstract
Similar to an electron in a solid, an impurity in an atomic Bose-Einstein condensate (BEC) is dressed by excitations from the medium, forming a polaron quasiparticle with modified properties. This impurity can also undergo chemical recombination with atoms from the BEC, a process resonantly enhanced when universal three-body Efimov bound states cross the continuum. To study the interplay between these phenomena, we use a Gaussian state variational method able to describe both Efimov physics and arbitrarily many excitations of the BEC. We show that the polaron cloud contributes to bound state formation, leading to a shift of the Efimov resonance to smaller interaction strengths. This shifted scattering resonance marks the onset of a polaronic instability towards the decay into large Efimov clusters and fast recombination, offering a remarkable example of chemistry in a quantum medium.
Collapse
Affiliation(s)
- Arthur Christianen
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 Munich, Germany
| | - J Ignacio Cirac
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 Munich, Germany
| | - Richard Schmidt
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 Munich, Germany
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
| |
Collapse
|
13
|
Wang J, Liu XJ, Hu H. Exact Quasiparticle Properties of a Heavy Polaron in BCS Fermi Superfluids. PHYSICAL REVIEW LETTERS 2022; 128:175301. [PMID: 35570441 DOI: 10.1103/physrevlett.128.175301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 04/04/2022] [Indexed: 06/15/2023]
Abstract
We present the Ramsey response and radio-frequency spectroscopy of a heavy impurity immersed in an interacting Fermi superfluid, using the exact functional determinant approach. We describe the Fermi superfluid through the conventional Bardeen-Cooper-Schrieffer theory and investigate the role of the pairing gap on quasiparticle properties revealed by the two spectroscopies. The energy cost for pair breaking prevents Anderson's orthogonality catastrophe that occurs in a noninteracting Fermi gas and allows the existence of polaron quasiparticles in the exactly solvable heavy impurity limit. Hence, we rigorously confirm the remarkable features such as dark continuum, molecule-hole continuum, and repulsive polaron. For a magnetic impurity scattering at finite temperature, we predict additional resonances related to the subgap Yu-Shiba-Rusinov bound state, whose positions can be used to measure the superfluid pairing gap. For a nonmagnetic scattering at zero temperature, we surprisingly find undamped repulsive polarons. These exact results might be readily observed in quantum gas experiments with Bose-Fermi mixtures that have a large-mass ratio.
Collapse
Affiliation(s)
- Jia Wang
- Centre for Quantum Technology Theory, Swinburne University of Technology, Melbourne 3122, Australia
| | - Xia-Ji Liu
- Centre for Quantum Technology Theory, Swinburne University of Technology, Melbourne 3122, Australia
| | - Hui Hu
- Centre for Quantum Technology Theory, Swinburne University of Technology, Melbourne 3122, Australia
| |
Collapse
|
14
|
Chen XY, Duda M, Schindewolf A, Bause R, Bloch I, Luo XY. Suppression of Unitary Three-Body Loss in a Degenerate Bose-Fermi Mixture. PHYSICAL REVIEW LETTERS 2022; 128:153401. [PMID: 35499890 DOI: 10.1103/physrevlett.128.153401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 03/17/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
We study three-body loss in an ultracold mixture of a thermal Bose gas and a degenerate Fermi gas. We find that at unitarity, where the interspecies scattering length diverges, the usual inverse-square temperature scaling of the three-body loss found in nondegenerate systems is strongly modified and reduced with the increasing degeneracy of the Fermi gas. While the reduction of loss is qualitatively explained within the few-body scattering framework, a remaining suppression provides evidence for the long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions mediated by fermions between bosons. Our model based on RKKY interactions quantitatively reproduces the data without free parameters, and predicts one order of magnitude reduction of the three-body loss coefficient in the deeply Fermi-degenerate regime.
Collapse
Affiliation(s)
- Xing-Yan Chen
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| | - Marcel Duda
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| | - Andreas Schindewolf
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| | - Roman Bause
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| | - Immanuel Bloch
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
- Fakultät für Physik, Ludwig-Maximilians-Universität, 80799 München, Germany
| | - Xin-Yu Luo
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| |
Collapse
|
15
|
Abstract
We investigate the properties of a dilute gas of impurities embedded in an ultracold gas of bosons that forms a Bose–Einstein condensate (BEC). This work focuses mainly on the equation of state (EoS) of the impurity gas at zero temperature and the induced interaction between impurities mediated by the host bath. We use perturbative field-theory approaches, such as Hugenholtz–Pines formalism, in the weakly interacting regime. In turn, for strong interactions, we aim at non-perturbative techniques such as quantum–Monte Carlo (QMC) methods. Our findings agree with experimental observations for an ultra dilute gas of impurities, modeled in the framework of the single impurity problem; however, as the density of impurities increases, systematic deviations are displayed with respect to the one-body Bose polaron problem.
Collapse
|
16
|
Abstract
We present a comprehensive discussion of the ground-state properties of dilute D-dimensional Bose gas interacting with a few static impurities. Assuming the short-ranged character of the boson-impurity interaction, we calculated the energy of three- and two-dimensional Bose systems with one and two impurities immersed.
Collapse
|
17
|
Planella G, Cenni MFB, Acín A, Mehboudi M. Bath-Induced Correlations Enhance Thermometry Precision at Low Temperatures. PHYSICAL REVIEW LETTERS 2022; 128:040502. [PMID: 35148153 DOI: 10.1103/physrevlett.128.040502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 12/22/2021] [Indexed: 06/14/2023]
Abstract
We study the role of bath-induced correlations in temperature estimation of cold bosonic baths. Our protocol includes multiple probes, that are not interacting, nor are they initially correlated to each other. They interact with a bosonic sample and reach a nonthermal steady state, which is measured to estimate the temperature of the sample. It is well known that in the steady state such noninteracting probes may get correlated to each other and even entangled. Nonetheless, the impact of these correlations in metrology has not been deeply investigated yet. Here, we examine their role for thermometry of cold bosonic gases and show that, although being classical, bath-induced correlations can lead to significant enhancement of precision for thermometry. The improvement is especially important at low temperatures, where attaining high precision thermometry is particularly demanding. The proposed thermometry scheme does not require any precise dynamical control of the probes and tuning the parameters and is robust to noise in initial preparation, as it is built upon the steady state generated by the natural dissipative dynamics of the system. Therefore, our results put forward new possibilities in thermometry at low temperatures, of relevance, for instance, in cold gases and Bose-Einstein condensates.
Collapse
Affiliation(s)
- Guim Planella
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
- Facultat de Física, Universitat de Barcelona, 08028 Barcelona, Spain
- Institute for Theoretical Physics, Utrecht University, 3584 CS Utrecht, Netherlands
| | - Marina F B Cenni
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
| | - Antonio Acín
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
- ICREA-Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
| | - Mohammad Mehboudi
- ICFO-Institut de Ciencies Fotoniques, The Barcelona Institute of Science and Technology, 08860 Castelldefels (Barcelona), Spain
- Max-Planck-Institut für Quantenoptik, D-85748 Garching, Germany
- Département de Physique Appliquée, Université de Genève, 1211 Genève, Switzerland
| |
Collapse
|
18
|
Polaron-Depleton Transition in the Yrast Excitations of a One-Dimensional Bose Gas with a Mobile Impurity. CONDENSED MATTER 2022. [DOI: 10.3390/condmat7010015] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
We present exact numerical data for the lowest-energy momentum eigenstates (yrast states) of a repulsive spin impurity in a one-dimensional Bose gas using full configuration interaction quantum Monte Carlo (FCIQMC). As a stochastic extension of exact diagonalization, it is well suited for the study of yrast states of a lattice-renormalized model for a quantum gas. Yrast states carry valuable information about the dynamic properties of slow-moving mobile impurities immersed in a many-body system. Based on the energies and the first and second-order correlation functions of yrast states, we identify different dynamical regimes and the transitions between them: The polaron regime, where the impurity’s motion is affected by the Bose gas through a renormalized effective mass; a regime of a gray soliton that is weakly correlated with a stationary impurity, and the depleton regime, where the impurity occupies a dark or gray soliton. Extracting the depleton effective mass reveals a super heavy regime where the magnitude of the (negative) depleton mass exceeds the mass of the finite Bose gas.
Collapse
|
19
|
Weakly-Interacting Bose–Bose Mixtures from the Functional Renormalisation Group. CONDENSED MATTER 2022. [DOI: 10.3390/condmat7010009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/10/2022]
Abstract
We provide a detailed presentation of the functional renormalisation group (FRG) approach for weakly-interacting Bose–Bose mixtures, including a complete discussion on the RG equations. To test this approach, we examine thermodynamic properties of balanced three-dimensional Bose–Bose gases at zero and finite temperatures and find a good agreement with related works. We also study ground-state energies of repulsive Bose polarons by examining mixtures in the limit of infinite population imbalance. Finally, we discuss future applications of the FRG to novel problems in Bose–Bose mixtures and related systems.
Collapse
|
20
|
Abstract
Recent studies have demonstrated that higher than two-body bath-impurity correlations are not important for quantitatively describing the ground state of the Bose polaron. Motivated by the above, we employ the so-called Gross Ansatz (GA) approach to unravel the stationary and dynamical properties of the homogeneous one-dimensional Bose-polaron for different impurity momenta and bath-impurity couplings. We explicate that the character of the equilibrium state crossovers from the quasi-particle Bose polaron regime to the collective-excitation stationary dark-bright soliton for varying impurity momentum and interactions. Following an interspecies interaction quench the temporal orthogonality catastrophe is identified, provided that bath-impurity interactions are sufficiently stronger than the intraspecies bath ones, thus generalizing the results of the confined case. This catastrophe originates from the formation of dispersive shock wave structures associated with the zero-range character of the bath-impurity potential. For initially moving impurities, a momentum transfer process from the impurity to the dispersive shock waves via the exerted drag force is demonstrated, resulting in a final polaronic state with reduced velocity. Our results clearly demonstrate the crucial role of non-linear excitations for determining the behavior of the one-dimensional Bose polaron.
Collapse
|
21
|
Abstract
Quantized sound waves-phonons-govern the elastic response of crystalline materials, and also play an integral part in determining their thermodynamic properties and electrical response (for example, by binding electrons into superconducting Cooper pairs)1-3. The physics of lattice phonons and elasticity is absent in simulators of quantum solids constructed of neutral atoms in periodic light potentials: unlike real solids, traditional optical lattices are silent because they are infinitely stiff4. Optical-lattice realizations of crystals therefore lack some of the central dynamical degrees of freedom that determine the low-temperature properties of real materials. Here, we create an optical lattice with phonon modes using a Bose-Einstein condensate (BEC) coupled to a confocal optical resonator. Playing the role of an active quantum gas microscope, the multimode cavity QED system both images the phonons and induces the crystallization that supports phonons via short-range, photon-mediated atom-atom interactions. Dynamical susceptibility measurements reveal the phonon dispersion relation, showing that these collective excitations exhibit a sound speed dependent on the BEC-photon coupling strength. Our results pave the way for exploring the rich physics of elasticity in quantum solids, ranging from quantum melting transitions5 to exotic 'fractonic' topological defects6 in the quantum regime.
Collapse
|
22
|
Pascual G, Boronat J. Quasiparticle Nature of the Bose Polaron at Finite Temperature. PHYSICAL REVIEW LETTERS 2021; 127:205301. [PMID: 34860030 DOI: 10.1103/physrevlett.127.205301] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Accepted: 10/22/2021] [Indexed: 06/13/2023]
Abstract
The Bose polaron has attracted theoretical and experimental interest because the mobile impurity is surrounded by a bath that undergoes a superfluid-to-normal phase transition. Although many theoretical works have studied this system in its ground state, only a few analyze its behavior at finite temperature. We have studied the effect of temperature on a Bose polaron system performing ab initio path integral Monte Carlo simulations. This method is able to approach the critical temperature without losing accuracy, in contrast with perturbative approximations. We have calculated the polaron energy for the repulsive and attractive branches and we have observed an asymmetric behavior between the two branches. When the potential is repulsive, the polaron energy decreases when the temperature increases, and contrariwise for the attractive branch. Our results for the effective mass and the dynamical structure factor of the polaron show unambiguously that its quasiparticle nature disappears close to the critical temperature, in agreement with recent experimental findings. Finally, we have also estimated the fraction of bosons in the condensate as well as the superfluid fraction, and we have concluded that the impurity hinders the condensation of the rest of bosons.
Collapse
Affiliation(s)
- Gerard Pascual
- Departament de Física, Campus Nord B4-B5, Universitat Politècnica de Catalunya, E-08034 Barcelona, Spain
| | - Jordi Boronat
- Departament de Física, Campus Nord B4-B5, Universitat Politècnica de Catalunya, E-08034 Barcelona, Spain
| |
Collapse
|
23
|
Seetharam K, Shchadilova Y, Grusdt F, Zvonarev MB, Demler E. Dynamical Quantum Cherenkov Transition of Fast Impurities in Quantum Liquids. PHYSICAL REVIEW LETTERS 2021; 127:185302. [PMID: 34767413 DOI: 10.1103/physrevlett.127.185302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Accepted: 08/04/2021] [Indexed: 06/13/2023]
Abstract
The challenge of understanding the dynamics of a mobile impurity in an interacting quantum many-body medium comes from the necessity of including entanglement between the impurity and excited states of the environment in a wide range of energy scales. In this Letter, we investigate the motion of a finite mass impurity injected into a three-dimensional quantum Bose fluid as it starts shedding Bogoliubov excitations. We uncover a transition in the dynamics as the impurity's velocity crosses a critical value that depends on the strength of the interaction between the impurity and bosons as well as the impurity's recoil energy. We find that in injection experiments, the two regimes differ not only in the character of the impurity velocity abatement but also exhibit qualitative differences in the Loschmidt echo, density ripples excited in the Bose-Einstein condensate, and momentum distribution of scattered bosonic particles. The transition is a manifestation of a dynamical quantum Cherenkov effect and should be experimentally observable with ultracold atoms using Ramsey interferometry, rf spectroscopy, absorption imaging, and time-of-flight imaging.
Collapse
Affiliation(s)
- Kushal Seetharam
- Department of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Yulia Shchadilova
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Fabian Grusdt
- Department of Physics and Arnold Sommerfeld Center for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstrasse 37, München D-80333, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, D-80799 München, Germany
| | - Mikhail B Zvonarev
- Université Paris-Saclay, CNRS, LPTMS, 91405 Orsay, France
- Russian Quantum Center, Skolkovo, Moscow 143025, Russia
- St. Petersburg Department of V.A. Steklov Mathematical Institute of Russian Academy of Sciences, Fontanka 27, St. Petersburg 191023, Russia
| | - Eugene Demler
- Institute for Theoretical Physics, ETH Zürich, 8093 Zürich, Switzerland
| |
Collapse
|
24
|
Will M, Astrakharchik GE, Fleischhauer M. Polaron Interactions and Bipolarons in One-Dimensional Bose Gases in the Strong Coupling Regime. PHYSICAL REVIEW LETTERS 2021; 127:103401. [PMID: 34533353 DOI: 10.1103/physrevlett.127.103401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/03/2021] [Accepted: 08/04/2021] [Indexed: 06/13/2023]
Abstract
Bose polarons, quasiparticles composed of mobile impurities surrounded by cold Bose gas, can experience strong interactions mediated by the many-body environment and form bipolaron bound states. Here we present a detailed study of heavy polarons in a one-dimensional Bose gas by formulating a nonperturbative theory and complementing it with exact numerical simulations. We develop an analytic approach for weak boson-boson interactions and arbitrarily strong impurity-boson couplings. Our approach is based on a mean-field theory that accounts for deformations of the superfluid by the impurities and in this way minimizes quantum fluctuations. The mean-field equations are solved exactly in the Born-Oppenheimer approximation, leading to an analytic expression for the interaction potential of heavy polarons, which is found to be in excellent agreement with quantum Monte Carlo (QMC) results. In the strong coupling limit, the potential substantially deviates from the exponential form valid for weak coupling and has a linear shape at short distances. Taking into account the leading-order Born-Huang corrections, we calculate bipolaron binding energies for impurity-boson mass ratios as low as 3 and find excellent agreement with QMC results.
Collapse
Affiliation(s)
- M Will
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| | - G E Astrakharchik
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034, Barcelona, Spain
| | - M Fleischhauer
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| |
Collapse
|
25
|
Levinsen J, Ardila LAP, Yoshida SM, Parish MM. Quantum Behavior of a Heavy Impurity Strongly Coupled to a Bose Gas. PHYSICAL REVIEW LETTERS 2021; 127:033401. [PMID: 34328775 DOI: 10.1103/physrevlett.127.033401] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 06/24/2021] [Indexed: 06/13/2023]
Abstract
We investigate the problem of an infinitely heavy impurity interacting with a dilute Bose gas at zero temperature. When the impurity-boson interactions are short-ranged, we show that boson-boson interactions induce a quantum blockade effect, where a single boson can effectively block or screen the impurity potential. Since this behavior depends on the quantum granular nature of the Bose gas, it cannot be captured within a standard classical-field description. Using a combination of exact quantum Monte Carlo methods and a truncated basis approach, we show how the quantum correlations between bosons lead to universal few-body bound states and a logarithmically slow dependence of the polaron ground-state energy on the boson-boson scattering length. Moreover, we expose the link between the polaron energy and the spatial structure of the quantum correlations, spanning the infrared to ultraviolet physics.
Collapse
Affiliation(s)
- Jesper Levinsen
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| | - Luis A Peña Ardila
- Institut für Theoretische Physik, Leibniz Universität, 30167 Hannover, Germany
| | - Shuhei M Yoshida
- Biometrics Research Laboratories, NEC Corporation, Kanagawa 211-8666, Japan
| | - Meera M Parish
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| |
Collapse
|
26
|
Christensen ER, Camacho-Guardian A, Bruun GM. Charged Polarons and Molecules in a Bose-Einstein Condensate. PHYSICAL REVIEW LETTERS 2021; 126:243001. [PMID: 34213934 DOI: 10.1103/physrevlett.126.243001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Accepted: 05/20/2021] [Indexed: 06/13/2023]
Abstract
Ultracold hybrid ion-atom gases represent an exciting frontier for quantum simulation offering a new set of functionalities and control. Here, we study a mobile ion immersed in a Bose-Einstein condensate and show that the long-range nature of the ion-atom interaction gives rise to an intricate interplay between few- and many-body physics. This leads to the existence of several polaronic and molecular states due to the binding of an increasing number of bosons to the ion, which is well beyond what can be described by a short-range pseudopotential. We use a complementary set of techniques including a variational ansatz and field theory to describe this rich physics and calculate the full spectral response of the ion. It follows from thermodynamic arguments that the ion-atom interaction leads to a mesoscopic dressing cloud of the polarons, and a simplified model demonstrates that the spectral weight of the molecules scale with increasing powers of the density. We finally calculate the quantum dynamics of the ion after a quench experiment.
Collapse
Affiliation(s)
- Esben Rohan Christensen
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
| | - Arturo Camacho-Guardian
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
- T.C.M. Group, Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Georg M Bruun
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
27
|
Abstract
An impurity immersed in a medium constitutes a canonical scenario applicable in a wide range of fields in physics. Though our understanding has advanced significantly in the past decades, quantum impurities in a bosonic environment are still of considerable theoretical and experimental interest. Here, we discuss the initial dynamics of such impurities, which was recently observed in interferometric experiments. Experimental observations from weak to unitary interactions are presented and compared to a theoretical description. In particular, the transition between two initial dynamical regimes dominated by two-body interactions is analyzed, yielding transition times in clear agreement with the theoretical prediction. Additionally, the distinct time dependence of the coherence amplitude in these regimes is obtained by extracting its power-law exponents. This benchmarks our understanding and suggests new ways of probing dynamical properties of quantum impurities.
Collapse
|
28
|
Massignan P, Yegovtsev N, Gurarie V. Universal Aspects of a Strongly Interacting Impurity in a Dilute Bose Condensate. PHYSICAL REVIEW LETTERS 2021; 126:123403. [PMID: 33834819 DOI: 10.1103/physrevlett.126.123403] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 02/16/2021] [Indexed: 06/12/2023]
Abstract
We study the properties of an impurity immersed in a weakly interacting Bose gas, i.e., of a Bose polaron. In the perturbatively tractable limit of weak impurity-boson interactions many of its properties are known to depend only on the scattering length. Here we demonstrate that for strong (unitary) impurity-boson interactions all quasiparticle properties of a heavy Bose polaron, such as its energy, its residue, its Tan's contact, and the number of bosons trapped nearby the impurity, depend on the impurity-boson potential via a single parameter characterizing its range.
Collapse
Affiliation(s)
- Pietro Massignan
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona, Spain
| | - Nikolay Yegovtsev
- Department of Physics and Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Victor Gurarie
- Department of Physics and Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| |
Collapse
|
29
|
Xiao K, Yan T, Liu Q, Yang S, Kan C, Duan R, Liu Z, Cui X. Many-Body Effect on Optical Properties of Monolayer Molybdenum Diselenide. J Phys Chem Lett 2021; 12:2555-2561. [PMID: 33683894 DOI: 10.1021/acs.jpclett.1c00320] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Excitons in monolayer transition metal dichalcogenides (TMDs) provide a paradigm of composite Boson in a two-dimensional system. This Letter reports a photoluminescence and reflectance study of excitons in monolayer molybdenum diselenide (MoSe2) with electrostatic gating. We observe the repulsive and attractive Fermi polaron modes of the band edge exciton, its excited state, and the spin-off excitons, which the simple three-particle trion model is insufficient to explain. The contrasting energy shift between the exciton and charge-bound excitons (repulsive and attractive polaron modes) and the remarkably different gate dependence of the polaron energy splitting between the ground state and the excited state excitons unambiguously support the Fermi polaron picture for excitons in monolayer TMDs.
Collapse
Affiliation(s)
- Ke Xiao
- Department of Physics, University of Hong Kong, Hong Kong, Hong Kong SAR
| | - Tengfei Yan
- Graduate School of China Academy of Engineering Physics, Beijing 100193, China
| | - Qiye Liu
- Department of Physics, University of Hong Kong, Hong Kong, Hong Kong SAR
| | - Siyuan Yang
- Department of Physics, University of Hong Kong, Hong Kong, Hong Kong SAR
| | - Chiming Kan
- Department of Physics, University of Hong Kong, Hong Kong, Hong Kong SAR
| | - Ruihuan Duan
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798
| | - Zheng Liu
- School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798
| | - Xiaodong Cui
- Department of Physics, University of Hong Kong, Hong Kong, Hong Kong SAR
| |
Collapse
|
30
|
Polaron Problems in Ultracold Atoms: Role of a Fermi Sea across Different Spatial Dimensions and Quantum Fluctuations of a Bose Medium. ATOMS 2021. [DOI: 10.3390/atoms9010018] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The notion of a polaron, originally introduced in the context of electrons in ionic lattices, helps us to understand how a quantum impurity behaves when being immersed in and interacting with a many-body background. We discuss the impact of the impurities on the medium particles by considering feedback effects from polarons that can be realized in ultracold quantum gas experiments. In particular, we exemplify the modifications of the medium in the presence of either Fermi or Bose polarons. Regarding Fermi polarons we present a corresponding many-body diagrammatic approach operating at finite temperatures and discuss how mediated two- and three-body interactions are implemented within this framework. Utilizing this approach, we analyze the behavior of the spectral function of Fermi polarons at finite temperature by varying impurity-medium interactions as well as spatial dimensions from three to one. Interestingly, we reveal that the spectral function of the medium atoms could be a useful quantity for analyzing the transition/crossover from attractive polarons to molecules in three-dimensions. As for the Bose polaron, we showcase the depletion of the background Bose-Einstein condensate in the vicinity of the impurity atom. Such spatial modulations would be important for future investigations regarding the quantification of interpolaron correlations in Bose polaron problems.
Collapse
|
31
|
Camacho-Guardian A, Bastarrachea-Magnani MA, Bruun GM. Mediated Interactions and Photon Bound States in an Exciton-Polariton Mixture. PHYSICAL REVIEW LETTERS 2021; 126:017401. [PMID: 33480782 DOI: 10.1103/physrevlett.126.017401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 05/13/2020] [Accepted: 12/08/2020] [Indexed: 06/12/2023]
Abstract
The quest to realize strongly interacting photons remains an outstanding challenge both for fundamental science and for applications. Here, we explore mediated photon-photon interactions in a highly imbalanced two-component mixture of exciton polaritons in a semiconductor microcavity. Using a theory that takes into account nonperturbative correlations between the excitons as well as strong light-matter coupling, we demonstrate the high tunability of an effective interaction between quasiparticles formed by minority component polaritons interacting with a Bose-Einstein condensate (BEC) of a majority component polaritons. In particular, the interaction, which is mediated by sound modes in the BEC can be made strong enough to support a bound state of two quasiparticles. Since these quasiparticles consist partly of photons, this in turn corresponds to a dimer state of photons propagating through the BEC. This gives rise to a new light transmission line where the dimer wave function is directly mapped onto correlations between the photons. Our findings open new routes for highly nonlinear optical materials and novel hybrid light-matter quantum systems.
Collapse
Affiliation(s)
- A Camacho-Guardian
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, 8000 Aarhus C, Denmark
| | | | - G M Bruun
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, 8000 Aarhus C, Denmark
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| |
Collapse
|
32
|
Adlong HS, Liu WE, Scazza F, Zaccanti M, Oppong ND, Fölling S, Parish MM, Levinsen J. Quasiparticle Lifetime of the Repulsive Fermi Polaron. PHYSICAL REVIEW LETTERS 2020; 125:133401. [PMID: 33034470 DOI: 10.1103/physrevlett.125.133401] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 07/20/2020] [Accepted: 08/24/2020] [Indexed: 06/11/2023]
Abstract
We investigate the metastable repulsive branch of a mobile impurity coupled to a degenerate Fermi gas via short-range interactions. We show that the quasiparticle lifetime of this repulsive Fermi polaron can be experimentally probed by driving Rabi oscillations between weakly and strongly interacting impurity states. Using a time-dependent variational approach, we find that we can accurately model the impurity Rabi oscillations that were recently measured for repulsive Fermi polarons in both two and three dimensions. Crucially, our theoretical description does not include relaxation processes to the lower-lying attractive branch. Thus, the theory-experiment agreement demonstrates that the quasiparticle lifetime is dominated by many-body dephasing within the upper repulsive branch rather than by relaxation from the upper branch itself. Our findings shed light on recent experimental observations of persistent repulsive correlations, and have important consequences for the nature and stability of the strongly repulsive Fermi gas.
Collapse
Affiliation(s)
- Haydn S Adlong
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
| | - Weizhe Edward Liu
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| | - Francesco Scazza
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO) and European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
| | - Matteo Zaccanti
- Istituto Nazionale di Ottica del Consiglio Nazionale delle Ricerche (CNR-INO) and European Laboratory for Nonlinear Spectroscopy (LENS), 50019 Sesto Fiorentino, Italy
| | - Nelson Darkwah Oppong
- Ludwig-Maximilians-Universität, Schellingstraße 4, 80799 München, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, 80799 München, Germany
| | - Simon Fölling
- Ludwig-Maximilians-Universität, Schellingstraße 4, 80799 München, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, 80799 München, Germany
| | - Meera M Parish
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| | - Jesper Levinsen
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| |
Collapse
|
33
|
Liu WE, Shi ZY, Levinsen J, Parish MM. Radio-Frequency Response and Contact of Impurities in a Quantum Gas. PHYSICAL REVIEW LETTERS 2020; 125:065301. [PMID: 32845677 DOI: 10.1103/physrevlett.125.065301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 06/04/2020] [Accepted: 07/07/2020] [Indexed: 06/11/2023]
Abstract
We investigate the radio-frequency spectroscopy of impurities interacting with a quantum gas at finite temperature. In the limit of a single impurity, we show using Fermi's golden rule that introducing (or injecting) an impurity into the medium is equivalent to ejecting an impurity that is initially interacting with the medium, since the "injection" and "ejection" spectral responses are simply related to each other by an exponential function of frequency. Thus, the full spectral information for the quantum impurity is contained in the injection spectral response, which can be determined using a range of theoretical methods, including variational approaches. We use this property to compute the finite-temperature equation of state and Tan contact of the Fermi polaron. Our results for the contact of a mobile impurity are in excellent agreement with recent experiments and we find that the finite-temperature behavior is qualitatively different compared to the case of infinite impurity mass.
Collapse
Affiliation(s)
- Weizhe Edward Liu
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| | - Zhe-Yu Shi
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, China
| | - Jesper Levinsen
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| | - Meera M Parish
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| |
Collapse
|
34
|
Nielsen KK, Camacho-Guardian A, Bruun GM, Pohl T. Superfluid Flow of Polaron Polaritons above Landau's Critical Velocity. PHYSICAL REVIEW LETTERS 2020; 125:035301. [PMID: 32745417 DOI: 10.1103/physrevlett.125.035301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2020] [Accepted: 06/19/2020] [Indexed: 06/11/2023]
Abstract
We develop a theory for the interaction of light with superfluid optical media, describing the motion of quantum impurities that are created and dragged through the liquid by propagating photons. It is well known that a mobile impurity suffers dissipation due to phonon emission as soon as it moves faster than the speed of sound in the superfluid-Landau's critical velocity. Surprisingly we find that in the present hybrid light-matter setting, polaritonic impurities can be protected against environmental decoherence and be allowed to propagate well above the Landau velocity without jeopardizing the superfluid response of the medium.
Collapse
Affiliation(s)
- K Knakkergaard Nielsen
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, 8000 Aarhus C, Denmark
| | - A Camacho-Guardian
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, 8000 Aarhus C, Denmark
| | - G M Bruun
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, 8000 Aarhus C, Denmark
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - T Pohl
- Department of Physics and Astronomy, Aarhus University, Ny Munkegade, 8000 Aarhus C, Denmark
| |
Collapse
|
35
|
Dzsotjan D, Schmidt R, Fleischhauer M. Dynamical Variational Approach to Bose Polarons at Finite Temperatures. PHYSICAL REVIEW LETTERS 2020; 124:223401. [PMID: 32567929 DOI: 10.1103/physrevlett.124.223401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2019] [Accepted: 05/13/2020] [Indexed: 06/11/2023]
Abstract
We discuss the interaction of a mobile quantum impurity with a Bose-Einstein condensate of atoms at finite temperature. To describe the resulting Bose polaron formation we develop a dynamical variational approach applicable to an initial thermal gas of Bogoliubov phonons. We study the polaron formation after switching on the interaction, e.g., by a radio-frequency (rf) pulse from a noninteracting to an interacting state. To treat also the strongly interacting regime, interaction terms beyond the Fröhlich model are taken into account. We calculate the real-time impurity Green's function and discuss its temperature dependence. Furthermore we determine the rf absorption spectrum and find good agreement with recent experimental observations. We predict temperature-induced shifts and a substantial broadening of spectral lines. The analysis of the real-time Green's function reveals a crossover to a linear temperature dependence of the thermal decay rate of Bose polarons as unitary interactions are approached.
Collapse
Affiliation(s)
- David Dzsotjan
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
- Wigner Research Center, Konkoly-Thege ut 29-33, 1121 Budapest, Hungary
| | - Richard Schmidt
- Max-Planck-Institute of Quantum Optics, Hans-Kopfermann-Strasse. 1, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 München, Germany
| | - Michael Fleischhauer
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, 67663 Kaiserslautern, Germany
| |
Collapse
|
36
|
Li X, Yakaboylu E, Bighin G, Schmidt R, Lemeshko M, Deuchert A. Intermolecular forces and correlations mediated by a phonon bath. J Chem Phys 2020; 152:164302. [PMID: 32357791 DOI: 10.1063/1.5144759] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Inspired by the possibility to experimentally manipulate and enhance chemical reactivity in helium nanodroplets, we investigate the effective interaction and the resulting correlations between two diatomic molecules immersed in a bath of bosons. By analogy with the bipolaron, we introduce the biangulon quasiparticle describing two rotating molecules that align with respect to each other due to the effective attractive interaction mediated by the excitations of the bath. We study this system in different parameter regimes and apply several theoretical approaches to describe its properties. Using a Born-Oppenheimer approximation, we investigate the dependence of the effective intermolecular interaction on the rotational state of the two molecules. In the strong-coupling regime, a product-state ansatz shows that the molecules tend to have a strong alignment in the ground state. To investigate the system in the weak-coupling regime, we apply a one-phonon excitation variational ansatz, which allows us to access the energy spectrum. In comparison to the angulon quasiparticle, the biangulon shows shifted angulon instabilities and an additional spectral instability, where resonant angular momentum transfer between the molecules and the bath takes place. These features are proposed as an experimentally observable signature for the formation of the biangulon quasiparticle. Finally, by using products of single angulon and bare impurity wave functions as basis states, we introduce a diagonalization scheme that allows us to describe the transition from two separated angulons to a biangulon as a function of the distance between the two molecules.
Collapse
Affiliation(s)
- Xiang Li
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Enderalp Yakaboylu
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Giacomo Bighin
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Richard Schmidt
- Max Planck Institute of Quantum Optics, Hans-Kopfermann-Str. 1, 85748 Garching, Germany
| | - Mikhail Lemeshko
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Andreas Deuchert
- IST Austria (Institute of Science and Technology Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| |
Collapse
|
37
|
Yan ZZ, Ni Y, Robens C, Zwierlein MW. Bose polarons near quantum criticality. Science 2020; 368:190-194. [DOI: 10.1126/science.aax5850] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 03/13/2020] [Indexed: 11/02/2022]
Affiliation(s)
- Zoe Z. Yan
- MIT–Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yiqi Ni
- MIT–Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Carsten Robens
- MIT–Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Martin W. Zwierlein
- MIT–Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| |
Collapse
|
38
|
Badrutdinov AO, Rees DG, Lin JY, Smorodin AV, Konstantinov D. Unidirectional Charge Transport via Ripplonic Polarons in a Three-Terminal Microchannel Device. PHYSICAL REVIEW LETTERS 2020; 124:126803. [PMID: 32281854 DOI: 10.1103/physrevlett.124.126803] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2019] [Revised: 01/13/2020] [Accepted: 02/28/2020] [Indexed: 06/11/2023]
Abstract
We study the transport of surface electrons on superfluid helium through a microchannel structure in which the charge flow splits into two branches, one flowing straight and one turned at 90°. According to Ohm's law, an equal number of charges should flow into each branch. However, when the electrons are dressed by surface excitations (ripplons) to form polaronlike particles with sufficiently large effective mass, all the charge follows the straight path due to momentum conservation. This surface-wave induced transport is analogous to the motion of electrons coupled to surface acoustic waves in semiconductor 2DEGs.
Collapse
Affiliation(s)
- A O Badrutdinov
- Okinawa Institute of Science and Technology, Tancha 1919-1, Okinawa 904-0495, Japan
| | - D G Rees
- NCTU-RIKEN Joint Research Laboratory, Institute of Physics, National Chiao Tung University, Hsinchu 300, Taiwan
- RIKEN CEMS, Wako 351-0198, Japan
| | - J Y Lin
- Okinawa Institute of Science and Technology, Tancha 1919-1, Okinawa 904-0495, Japan
| | - A V Smorodin
- Okinawa Institute of Science and Technology, Tancha 1919-1, Okinawa 904-0495, Japan
| | - D Konstantinov
- Okinawa Institute of Science and Technology, Tancha 1919-1, Okinawa 904-0495, Japan
| |
Collapse
|
39
|
A Dual-Species Bose-Einstein Condensate with Attractive Interspecies Interactions. CONDENSED MATTER 2020. [DOI: 10.3390/condmat5010021] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We report on the production of a 41 K- 87 Rb dual-species Bose–Einstein condensate with tunable interspecies interaction and we study the mixture in the attractive regime; i.e., for negative values of the interspecies scattering length a 12 . The binary condensate is prepared in the ground state and confined in a pure optical trap. We exploit Feshbach resonances for tuning the value of a 12 . After compensating the gravitational sag between the two species with a magnetic field gradient, we drive the mixture into the attractive regime. We let the system evolve both in free space and in an optical waveguide. In both geometries, for strong attractive interactions, we observe the formation of self-bound states, recognizable as quantum droplets. Our findings prove that robust, long-lived droplet states can be realized in attractive two-species mixtures, despite the two atomic components possibly experiencing different potentials.
Collapse
|
40
|
Levinsen J, Marchetti FM, Keeling J, Parish MM. Spectroscopic Signatures of Quantum Many-Body Correlations in Polariton Microcavities. PHYSICAL REVIEW LETTERS 2019; 123:266401. [PMID: 31951450 DOI: 10.1103/physrevlett.123.266401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2018] [Revised: 09/19/2018] [Indexed: 06/10/2023]
Abstract
We theoretically investigate the many-body states of exciton polaritons that can be observed by pump-probe spectroscopy in high-Q inorganic microcavities. Here, a weak-probe "spin-down" polariton is introduced into a coherent state of "spin-up" polaritons created by a strong pump. We show that the ↓ impurities become dressed by excitations of the ↑ medium, and that they form new polaronic quasiparticles that feature two-point and three-point many-body quantum correlations that, in the low density regime, arise from coupling to the vacuum biexciton and triexciton states, respectively. In particular, we find that these correlations generate additional branches and avoided crossings in the ↓ optical transmission spectrum that have a characteristic dependence on the ↑-polariton density. Our results thus demonstrate a way to directly observe correlated many-body states in an exciton-polariton system that go beyond classical mean-field theories.
Collapse
Affiliation(s)
- Jesper Levinsen
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| | - Francesca Maria Marchetti
- Departamento de Física Teórica de la Materia Condensada & Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid, Madrid 28049, Spain
| | - Jonathan Keeling
- SUPA, School of Physics and Astronomy, University of St Andrews, St. Andrews KY16 9SS, United Kingdom
| | - Meera M Parish
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| |
Collapse
|
41
|
Wang J, Liu XJ, Hu H. Roton-Induced Bose Polaron in the Presence of Synthetic Spin-Orbit Coupling. PHYSICAL REVIEW LETTERS 2019; 123:213401. [PMID: 31809177 DOI: 10.1103/physrevlett.123.213401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Indexed: 06/10/2023]
Abstract
We predict the existence of a roton-induced Bose polaron for an impurity immersed in a three-dimensional Bose-Einstein condensate with Raman-laser-induced spin-orbit coupling, where the condensate is in a finite-momentum plane-wave state with an intriguing roton minimum in its excitation spectrum. This novel polaron is formed by dressing the impurity with roton excitations, instead of phonon excitations as in a conventional (i.e., phonon-induced) Bose polaron, and acquires a significant center-of-mass momentum and highly anisotropic effective mass. We find that the roton-induced polaron evolves from a phonon-induced polaron, as the interaction between impurity and atoms increases across a Feshbach resonance. The evolution is not smooth, and a first-order phase transition from a phonon- to roton-induced polaron is observed at a critical interaction strength.
Collapse
Affiliation(s)
- Jia Wang
- Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne 3122, Australia
| | - Xia-Ji Liu
- Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne 3122, Australia
| | - Hui Hu
- Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne 3122, Australia
| |
Collapse
|
42
|
Ashida Y, Shi T, Schmidt R, Sadeghpour HR, Cirac JI, Demler E. Quantum Rydberg Central Spin Model. PHYSICAL REVIEW LETTERS 2019; 123:183001. [PMID: 31763913 DOI: 10.1103/physrevlett.123.183001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Indexed: 06/10/2023]
Abstract
We consider dynamics of a Rydberg impurity in a cloud of ultracold bosonic atoms in which the Rydberg electron undergoes spin-changing collisions with surrounding atoms. This system realizes a new type of quantum impurity problems that compounds essential features of the Kondo model, the Bose polaron, and the central spin model. To capture the interplay of the Rydberg-electron spin dynamics and the orbital motion of atoms, we employ a new variational method that combines an impurity-decoupling transformation with a Gaussian ansatz for the bath particles. We find several unexpected features of this model that are not present in traditional impurity problems, including interaction-induced renormalization of the absorption spectrum that eludes simple explanations from molecular bound states, and long-lasting oscillations of the Rydberg-electron spin. We discuss generalizations of our analysis to other systems in atomic physics and quantum chemistry, where an electron excitation of high orbital quantum number interacts with a spinful quantum bath.
Collapse
Affiliation(s)
- Yuto Ashida
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Tao Shi
- CAS Key Laboratory of Theoretical Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Richard Schmidt
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse. 1, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 München, Germany
| | - H R Sadeghpour
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
| | - J Ignacio Cirac
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse. 1, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 München, Germany
| | - Eugene Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| |
Collapse
|
43
|
Sinha S, Sinha S. Dissipative Bose-Josephson junction coupled to bosonic baths. Phys Rev E 2019; 100:032115. [PMID: 31640056 DOI: 10.1103/physreve.100.032115] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Indexed: 11/07/2022]
Abstract
We investigate the effect of dissipation in a Bose-Josephson junction (BJJ) coupled to baths of bosons at its two sites. Apart from the dynamical transition due to repulsive interactions, the BJJ undergoes a quantum phase transition by increasing the coupling strength with the bath modes. We analyze this system by mapping to an equivalent spin model coupled to the bosonic modes. The excitation energies and fluctuation of number imbalance are obtained within a Holstein-Primakoff approximation, which exhibits vanishing of the energy gap and enhanced quantum fluctuations at the critical point. We study the dynamics of BJJ using a time-dependent variational method and analyze stability of different types of steady states. As a special case we study in detail the phase space dynamics of BJJ coupled to a single mode, which reveals diffusive and incoherent behavior with increasing coupling to the bath mode. The dynamical steady states corresponding to the π oscillation and self-trapped state become unstable when their oscillation frequencies are in resonance with the bath modes. We study the Josephson dynamics in the presence of an Ohmic bath with Gaussian noise to incorporate the thermal fluctuations and obtain the Josephson oscillation frequency and damping analytically. We also observe the transition to the symmetry-broken state for strong coupling as well as decay of π oscillation and a self-trapped state to the ground state due to dissipation. Variation of the phase fluctuation with temperature of the bath shows similar behavior as observed in experiment. Finally we discuss the experimental setup to study the observable effects of dissipation in BJJ.
Collapse
Affiliation(s)
- Sudip Sinha
- Indian Institute of Science Education and Research-Kolkata, Mohanpur, Nadia-741246, India
| | - S Sinha
- Indian Institute of Science Education and Research-Kolkata, Mohanpur, Nadia-741246, India
| |
Collapse
|
44
|
Pierce M, Leyronas X, Chevy F. Few Versus Many-Body Physics of an Impurity Immersed in a Superfluid of Spin 1/2 Attractive Fermions. PHYSICAL REVIEW LETTERS 2019; 123:080403. [PMID: 31491212 DOI: 10.1103/physrevlett.123.080403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 06/12/2019] [Indexed: 06/10/2023]
Abstract
In this Letter we investigate the properties of an impurity immersed in a superfluid of strongly correlated spin 1/2 fermions and we calculate the beyond-mean-field corrections to the energy of a weakly interacting impurity. We show that these corrections are divergent and have to be regularized by properly accounting for three-body physics in the problem and that our approach naturally provides a unifying framework for Bose and Fermi polaron physics.
Collapse
Affiliation(s)
- M Pierce
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 75005 Paris France
| | - X Leyronas
- Laboratoire de physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, 75005 Paris France
| | - F Chevy
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 75005 Paris France
| |
Collapse
|
45
|
Liu WE, Levinsen J, Parish MM. Variational Approach for Impurity Dynamics at Finite Temperature. PHYSICAL REVIEW LETTERS 2019; 122:205301. [PMID: 31172772 DOI: 10.1103/physrevlett.122.205301] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Indexed: 06/09/2023]
Abstract
We present a general variational principle for the dynamics of impurity particles immersed in a quantum-mechanical medium. By working within the Heisenberg picture and constructing approximate time-dependent impurity operators, we can take the medium to be in any mixed state, such as a thermal state. Our variational method is consistent with all conservation laws and, in certain cases, it is equivalent to a finite-temperature Green's function approach. As a demonstration of our method, we consider the dynamics of heavy impurities that have suddenly been introduced into a Fermi gas at finite temperature. Using approximate time-dependent impurity operators involving only one particle-hole excitation of the Fermi sea, we find that we can successfully model the results of recent Ramsey interference experiments on ^{40}K atoms in a ^{6}Li Fermi gas. We also show that our approximation agrees well with the exact solution for the Ramsey response of a fixed impurity at finite temperature. Our approach paves the way for the investigation of impurities with dynamical degrees of freedom in arbitrary quantum-mechanical mediums.
Collapse
Affiliation(s)
- Weizhe Edward Liu
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| | - Jesper Levinsen
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| | - Meera M Parish
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Monash University, Victoria 3800, Australia
| |
Collapse
|
46
|
Mistakidis SI, Katsimiga GC, Koutentakis GM, Busch T, Schmelcher P. Quench Dynamics and Orthogonality Catastrophe of Bose Polarons. PHYSICAL REVIEW LETTERS 2019; 122:183001. [PMID: 31144905 DOI: 10.1103/physrevlett.122.183001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Indexed: 06/09/2023]
Abstract
We monitor the correlated quench induced dynamical dressing of a spinor impurity repulsively interacting with a Bose-Einstein condensate. Inspecting the temporal evolution of the structure factor, three distinct dynamical regions arise upon increasing the interspecies interaction. These regions are found to be related to the segregated nature of the impurity and to the Ohmic character of the bath. It is shown that the impurity dynamics can be described by an effective potential that deforms from a harmonic to a double-well one when crossing the miscibility-immiscibility threshold. In particular, for miscible components the polaron formation is imprinted on the spectral response of the system. We further illustrate that for increasing interaction an orthogonality catastrophe occurs and the polaron picture breaks down. Then a dissipative motion of the impurity takes place leading to a transfer of energy to its environment. This process signals the presence of entanglement in the many-body system.
Collapse
Affiliation(s)
- S I Mistakidis
- Center for Optical Quantum Technologies, Department of Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - G C Katsimiga
- Center for Optical Quantum Technologies, Department of Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - G M Koutentakis
- Center for Optical Quantum Technologies, Department of Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Th Busch
- Quantum Systems Unit, OIST Graduate University, Onna, Okinawa 904-0495, Japan
| | - P Schmelcher
- Center for Optical Quantum Technologies, Department of Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| |
Collapse
|
47
|
Navadeh-Toupchi M, Takemura N, Anderson MD, Oberli DY, Portella-Oberli MT. Polaritonic Cross Feshbach Resonance. PHYSICAL REVIEW LETTERS 2019; 122:047402. [PMID: 30768331 DOI: 10.1103/physrevlett.122.047402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Revised: 10/22/2018] [Indexed: 06/09/2023]
Abstract
We demonstrate the existence of a cross Feshbach resonance by strongly driving a lower polariton mode and by monitoring in time the transmission of a short optical pulse at the energy of the upper polariton mode in a semiconductor microcavity. From the signatures of the optical resonance, strength, and sign of the energy shift, we attribute the origin of the scattering process between polariton modes with opposite circular polarization to a biexciton bound state. From this study, we infer the conditions required for a strong enhancement of the generation of entangled photon pairs.
Collapse
Affiliation(s)
- M Navadeh-Toupchi
- Institute of Physics, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - N Takemura
- Institute of Physics, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - M D Anderson
- Institute of Physics, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - D Y Oberli
- Institute of Physics, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| | - M T Portella-Oberli
- Institute of Physics, School of Basic Sciences, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
| |
Collapse
|
48
|
Shi ZY, Yoshida SM, Parish MM, Levinsen J. Impurity-Induced Multibody Resonances in a Bose Gas. PHYSICAL REVIEW LETTERS 2018; 121:243401. [PMID: 30608757 DOI: 10.1103/physrevlett.121.243401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2018] [Indexed: 06/09/2023]
Abstract
We investigate the problem of N identical bosons that are coupled to an impurity particle with infinite mass. For noninteracting bosons, we show that a dynamical impurity-boson interaction, mediated by a closed-channel dimer, can induce an effective boson-boson repulsion which strongly modifies the bound states consisting of the impurity and N bosons. In particular, we demonstrate the existence of two universal "multibody" resonances, where all multibody bound states involving any N emerge and disappear. The first multibody resonance corresponds to infinite impurity-boson scattering length, a→+∞, while the second corresponds to the critical scattering length a^{*}>0 beyond which the trimer (N=2 bound state) ceases to exist. Crucially, we show that the existence of a^{*} ensures that the ground-state energy in the multibody bound-state region, ∞>a>a^{*}, is bounded from below, with a bound that is independent of N. Thus, even though the impurity can support multibody bound states, they become increasingly fragile beyond the dimer state. This has implications for the nature of the Bose polaron currently being studied in cold-atom experiments.
Collapse
Affiliation(s)
- Zhe-Yu Shi
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
| | - Shuhei M Yoshida
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
- Department of Physics, The University of Tokyo, Tokyo 113-0033, Japan
| | - Meera M Parish
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
| | - Jesper Levinsen
- School of Physics and Astronomy, Monash University, Victoria 3800, Australia
| |
Collapse
|
49
|
Trautmann A, Ilzhöfer P, Durastante G, Politi C, Sohmen M, Mark MJ, Ferlaino F. Dipolar Quantum Mixtures of Erbium and Dysprosium Atoms. PHYSICAL REVIEW LETTERS 2018; 121:213601. [PMID: 30517813 DOI: 10.1103/physrevlett.121.213601] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 10/08/2018] [Indexed: 06/09/2023]
Abstract
We report on the first realization of heteronuclear dipolar quantum mixtures of highly magnetic erbium and dysprosium atoms. With a versatile experimental setup, we demonstrate binary Bose-Einstein condensation in five different Er-Dy isotope combinations, as well as one Er-Dy Bose-Fermi mixture. Finally, we present first studies of the interspecies interaction between the two species for one mixture.
Collapse
Affiliation(s)
- A Trautmann
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - P Ilzhöfer
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
- Institut für Experimentalphysik und Zentrum für Quantenoptik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - G Durastante
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
- Institut für Experimentalphysik und Zentrum für Quantenoptik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - C Politi
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - M Sohmen
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
- Institut für Experimentalphysik und Zentrum für Quantenoptik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M J Mark
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
- Institut für Experimentalphysik und Zentrum für Quantenoptik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - F Ferlaino
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
- Institut für Experimentalphysik und Zentrum für Quantenoptik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| |
Collapse
|
50
|
Schmidt F, Mayer D, Bouton Q, Adam D, Lausch T, Spethmann N, Widera A. Quantum Spin Dynamics of Individual Neutral Impurities Coupled to a Bose-Einstein Condensate. PHYSICAL REVIEW LETTERS 2018; 121:130403. [PMID: 30312071 DOI: 10.1103/physrevlett.121.130403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2018] [Indexed: 06/08/2023]
Abstract
We report on spin dynamics of individual, localized neutral impurities immersed in a Bose-Einstein condensate. Single cesium atoms are transported into a cloud of rubidium atoms and thermalize with the bath, and the ensuing spin exchange between localized impurities with quasispin F_{i}=3 and bath atoms with F_{b}=1 is resolved. Comparing our data to numerical simulations of spin dynamics, we find that, for gas densities in the Bose-Einstein condensate regime, the dynamics is dominated by the condensed fraction of the cloud. We spatially resolve the density overlap of impurities and gas by the spin population of impurities. Finally, we trace the coherence of impurities prepared in a coherent superposition of internal states when coupled to a gas of different densities. For our choice of states, we show that, despite high bath densities and, thus, fast thermalization rates, the impurity coherence is not affected by the bath, realizing a regime of sympathetic cooling while maintaining internal state coherence. Our work paves the way toward the nondestructive probing of quantum many-body systems via localized impurities.
Collapse
Affiliation(s)
- Felix Schmidt
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany
| | - Daniel Mayer
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany
| | - Quentin Bouton
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany
| | - Daniel Adam
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany
| | - Tobias Lausch
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany
| | - Nicolas Spethmann
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany
| | - Artur Widera
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Germany
- Graduate School Materials Science in Mainz, Gottlieb-Daimler-Strasse 47, 67663 Kaiserslautern, Germany
| |
Collapse
|