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Borsi M, Pristyák L, Pozsgay B. Matrix Product Symmetries and Breakdown of Thermalization from Hard Rod Deformations. PHYSICAL REVIEW LETTERS 2023; 131:037101. [PMID: 37540872 DOI: 10.1103/physrevlett.131.037101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2023] [Accepted: 06/26/2023] [Indexed: 08/06/2023]
Abstract
We construct families of exotic spin-1/2 chains using a procedure called "hard rod deformation." We treat both integrable and nonintegrable examples. The models possess a large noncommutative symmetry algebra, which is generated by matrix product operators with a fixed small bond dimension. The symmetries lead to Hilbert space fragmentation and to the breakdown of thermalization. As an effect, the models support persistent oscillations in nonequilibrium situations. Similar symmetries have been reported earlier in integrable models, but here we show that they also occur in nonintegrable cases.
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Affiliation(s)
- Márton Borsi
- MTA-ELTE "Momentum" Integrable Quantum Dynamics Research Group, Department of Theoretical Physics, Eötvös Loránd University, 1053 Budapest, Hungary
| | - Levente Pristyák
- MTA-ELTE "Momentum" Integrable Quantum Dynamics Research Group, Department of Theoretical Physics, Eötvös Loránd University, 1053 Budapest, Hungary
- Department of Theoretical Physics, Budapest University of Technology and Economics, 1111 Budapest, Hungary
| | - Balázs Pozsgay
- MTA-ELTE "Momentum" Integrable Quantum Dynamics Research Group, Department of Theoretical Physics, Eötvös Loránd University, 1053 Budapest, Hungary
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2
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Cavazos-Cavazos D, Senaratne R, Kafle A, Hulet RG. Thermal disruption of a Luttinger liquid. Nat Commun 2023; 14:3154. [PMID: 37258570 DOI: 10.1038/s41467-023-38767-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Accepted: 05/15/2023] [Indexed: 06/02/2023] Open
Abstract
The Tomonaga-Luttinger liquid (TLL) theory describes the low-energy excitations of strongly correlated one-dimensional (1D) fermions. In the past years, a number of studies have provided a detailed understanding of this universality class. More recently, theoretical investigations that go beyond the standard low-temperature, linear-response TLL regime have been developed. While these provide a basis for understanding the dynamics of the spin-incoherent Luttinger liquid, there are few experimental investigations in this regime. Here we report the observation of a thermally induced, spin-incoherent Luttinger liquid in a 6Li atomic Fermi gas confined to 1D. We use Bragg spectroscopy to measure the suppression of spin-charge separation and the decay of correlations as the temperature is increased. Our results probe the crossover between the coherent and incoherent regimes of the Luttinger liquid and elucidate the roles of the charge and the spin degrees of freedom in this regime.
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Affiliation(s)
| | - Ruwan Senaratne
- Department of Physics and Astronomy, Rice University, Houston, Texas, 77005, USA
| | - Aashish Kafle
- Department of Physics and Astronomy, Rice University, Houston, Texas, 77005, USA
| | - Randall G Hulet
- Department of Physics and Astronomy, Rice University, Houston, Texas, 77005, USA.
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3
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Pâţu OI, Averin DV. Temperature-Dependent Periodicity of the Persistent Current in Strongly Interacting Systems. PHYSICAL REVIEW LETTERS 2022; 128:096801. [PMID: 35302823 DOI: 10.1103/physrevlett.128.096801] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2021] [Accepted: 02/14/2022] [Indexed: 06/14/2023]
Abstract
The persistent current in small isolated rings enclosing magnetic flux is the current circulating in equilibrium in the absence of an external excitation. While initially studied in superconducting and normal metals, recently, atomic persistent currents have been generated in ultracold gases spurring a new wave of theoretical investigations. Nevertheless, our understanding of the persistent currents in interacting systems is far from complete, especially at finite temperatures. Here we consider the fermionic one-dimensional Hubbard model and show that in the strong-interacting limit, the current can change its flux period and sign (diamagnetic or paramagnetic) as a function of temperature, features that cannot be explained within the single-particle or Luttinger liquid techniques. Also, the magnitude of the current can counterintuitively increase with temperature, in addition to presenting different rates of decay depending on the polarization of the system. Our work highlights the properties of the strongly interacting multicomponent systems that are missed by conventional approximation techniques, but can be important for the interpretation of experiments on persistent currents in ultracold gases.
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Affiliation(s)
- Ovidiu I Pâţu
- Institute for Space Sciences, Bucharest-Măgurele R 077125, Romania
| | - Dmitri V Averin
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
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4
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He F, Jiang YZ, Lin HQ, Hulet RG, Pu H, Guan XW. Emergence and Disruption of Spin-Charge Separation in One-Dimensional Repulsive Fermions. PHYSICAL REVIEW LETTERS 2020; 125:190401. [PMID: 33216574 DOI: 10.1103/physrevlett.125.190401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/27/2020] [Accepted: 09/17/2020] [Indexed: 06/11/2023]
Abstract
At low temperature, collective excitations of one-dimensional (1D) interacting fermions exhibit spin-charge separation, a unique feature predicted by the Tomonaga-Luttinger liquid (TLL) theory, but a rigorous understanding remains challenging. Using the thermodynamic Bethe ansatz (TBA) formalism, we analytically derive universal properties of a 1D repulsive spin-1/2 Fermi gas with arbitrary interaction strength. We show how spin-charge separation emerges from the exact TBA formalism, and how it is disrupted by the interplay between the two degrees of freedom that brings us beyond the TLL paradigm. Based on the exact low-lying excitation spectra, we further evaluate the spin and charge dynamical structure factors (DSFs). The peaks of the DSFs exhibit distinguishable propagating velocities of spin and charge as functions of interaction strength, which can be observed by Bragg spectroscopy with ultracold atoms.
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Affiliation(s)
- Feng He
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, APM, Chinese Academy of Sciences, Wuhan 430071, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yu-Zhu Jiang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, APM, Chinese Academy of Sciences, Wuhan 430071, China
| | - Hai-Qing Lin
- Beijing Computational Science Research Center, Beijing 100193, China
- Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Randall G Hulet
- Department of Physics and Astronomy, and Rice Center for Quantum Materials, Rice University, Houston, Texas 77251-1892, USA
| | - Han Pu
- Department of Physics and Astronomy, and Rice Center for Quantum Materials, Rice University, Houston, Texas 77251-1892, USA
| | - Xi-Wen Guan
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, APM, Chinese Academy of Sciences, Wuhan 430071, China
- Center for Cold Atom Physics, Chinese Academy of Sciences, Wuhan 430071, China
- Department of Theoretical Physics, Research School of Physics and Engineering, Australian National University, Canberra ACT 0200, Australia
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5
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Liang S, Zhang D, Chen W. Momentum distribution and tunneling density of states of one-dimensional Fermionic [Formula: see text] Hubbard model. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:185601. [PMID: 30726773 DOI: 10.1088/1361-648x/ab04be] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We study the one-dimensional Fermionic Hubbard model with [Formula: see text] spin symmetry in the incommensurate filling case. The basic properties of Green's function, momentum distribution and tunneling density of states of the system at low temperature are studied in the frame work of Luttinger liquid theory combined with Bethe Ansatz solutions for arbitrary interaction. In the strong interacting case, the system enters the spin-incoherent regime at intermediate temperature [Formula: see text] and we obtain the Green's function and tunneling density of states by generalizing the path integral approach for the [Formula: see text] case to the [Formula: see text] case in this regime. The theoretical results we obtained agree qualitatively with the experiments on the one-dimensional alkaline earth atomic system with [Formula: see text] spin symmetry. The similarities and difference between the one-dimensional [Formula: see text] Fermionic Hubbard system at large N and the one-dimensional spinless Bosonic system are also investigated.
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Affiliation(s)
- Shuang Liang
- Department of Physics, Nanjing University and National Laboratory of Solid State Microstructures, Nanjing 210093, People's Republic of China
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6
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Pâţu OI, Klümper A, Foerster A. Universality and Quantum Criticality of the One-Dimensional Spinor Bose Gas. PHYSICAL REVIEW LETTERS 2018; 120:243402. [PMID: 29956958 DOI: 10.1103/physrevlett.120.243402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Indexed: 06/08/2023]
Abstract
We investigate the universal thermodynamics of the two-component one-dimensional Bose gas with contact interactions in the vicinity of the quantum critical point separating the vacuum and the ferromagnetic liquid regime. We find that the quantum critical region belongs to the universality class of the spin-degenerate impenetrable particle gas which, surprisingly, is very different from the single-component case and identify its boundaries with the peaks of the specific heat. In addition, we show that the compressibility Wilson ratio, which quantifies the relative strength of thermal and quantum fluctuations, serves as a good discriminator of the quantum regimes near the quantum critical point. Remarkably, in the Tonks-Girardeau regime, the universal contact develops a pronounced minimum, reflected in a counterintuitive narrowing of the momentum distribution as we increase the temperature. This momentum reconstruction, also present at low and intermediate momenta, signals the transition from the ferromagnetic to the spin-incoherent Luttinger liquid phase and can be detected in current experiments with ultracold atomic gases in optical lattices.
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Affiliation(s)
- Ovidiu I Pâţu
- Institute for Space Sciences, Bucharest-Măgurele, R 077125 Romania
| | - Andreas Klümper
- Fakultät für Mathematik und Naturwissenschaften, Bergische Universität Wuppertal, 42097 Wuppertal, Germany
| | - Angela Foerster
- Instituto de Física da UFRGS, Avenida Bento Gonçalves 9500, Porto Alegre, Rio Grande do Sul, Brazil
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Schönhammer K. Physics in one dimension: theoretical concepts for quantum many-body systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:014001. [PMID: 23220952 DOI: 10.1088/0953-8984/25/1/014001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Various sophisticated approximation methods exist for the description of quantum many-body systems. It was realized early on that the theoretical description can simplify considerably in one-dimensional systems and various exact solutions exist. The focus in this introductory paper is on fermionic systems and the emergence of the Luttinger liquid concept.
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Affiliation(s)
- K Schönhammer
- Institut für Theoretische Physik, Universität Göttingen, Germany.
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8
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Micolich AP. What lurks below the last plateau: experimental studies of the 0.7 × 2e(2)/h conductance anomaly in one-dimensional systems. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:443201. [PMID: 21997403 DOI: 10.1088/0953-8984/23/44/443201] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The integer quantised conductance of one-dimensional electron systems is a well-understood effect of quantum confinement. A number of fractionally quantised plateaus are also commonly observed. They are attributed to many-body effects, but their precise origin is still a matter of debate, having attracted considerable interest over the past 15 years. This review reports on experimental studies of fractionally quantised plateaus in semiconductor quantum point contacts and quantum wires, focusing on the 0.7 × 2e(2)/h conductance anomaly, its analogues at higher conductances and the zero-bias peak observed in the dc source-drain bias for conductances less than 2e(2)/h.
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Affiliation(s)
- A P Micolich
- School of Physics, University of New South Wales, Sydney, NSW 2052, Australia.
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9
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Schmeltzer D. Dirac's method for constraints: an application to quantum wires. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2011; 23:155601. [PMID: 21460427 DOI: 10.1088/0953-8984/23/15/155601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We investigate the Hubbard model in the limit U = ∞, which is equivalent to the statistical condition of exclusion of double occupancy. We solve this problem using Dirac's method for constraints. The constraints are solved within the bosonization method. We find that the constraints modify the anomalous commutator. We apply this theory to quantum wires at finite temperatures where the Hubbard interaction is U = ∞. We find that the anomalous commutator induced by the constraints gives rise to the 0.7 anomalous conductance.
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Affiliation(s)
- D Schmeltzer
- Department of Physics, City College of the City University of New York, New York, NY 10031, USA
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10
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Schmeltzer D, Kuklov A, Malard M. A scaling approach for interacting quantum wires--a possible explanation for the 0.7 anomalous conductance. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2010; 22:095301. [PMID: 21389411 DOI: 10.1088/0953-8984/22/9/095301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
We consider a weakly interacting finite wire with short and long range interactions. The long range interactions enhance the 4k(F) scattering and renormalize the wire to a strongly interacting limit. For large screening lengths, the renormalized charge stiffness Luttinger parameter K(eff) decreases to [Formula: see text], giving rise to a Wigner crystal at T=0 with an anomalous conductance at finite temperatures. For short screening lengths, the renormalized Luttinger parameter K(eff) is restricted to ½≤K(eff)≤1. As a result, at temperatures larger than the magnetic exchange energy we find an interacting metal which, for K(eff)≈½, is equivalent to the Hubbard U−>∞ model, with the anomalous conductance G≈e(2)/h.
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Affiliation(s)
- D Schmeltzer
- Department of Physics, City College of the CUNY, USA
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11
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Fiete GA. Singular responses of spin-incoherent Luttinger liquids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2009; 21:193201. [PMID: 21825474 DOI: 10.1088/0953-8984/21/19/193201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
When a local potential changes abruptly in time, an electron gas responds by shifting to a new state which at long times is orthogonal to the one in the absence of the local potential. This is known as Anderson's orthogonality catastrophe and it is relevant for the so-called x-ray edge or Fermi-edge singularity, and for tunneling into an interacting one-dimensional system of fermions. It often happens that the finite frequency response of the photon absorption or the tunneling density of states exhibits a singular behavior as a function of frequency: [Formula: see text], where ω(th) is a threshold frequency and α is an exponent characterizing the singular response. In this review singular responses of spin-incoherent Luttinger liquids are reviewed. Such responses most often do not fall into the familiar form above, but instead typically exhibit logarithmic corrections and display a much higher universality in terms of the microscopic interactions in the theory. Specific predictions are made, the current experimental situation is summarized and key outstanding theoretical issues related to spin-incoherent Luttinger liquids are highlighted.
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Affiliation(s)
- Gregory A Fiete
- Department of Physics, University of Texas at Austin, Austin, TX 78712, USA
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12
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Matveev KA, Furusaki A. Spectral functions of strongly interacting isospin-1/2 bosons in one dimension. PHYSICAL REVIEW LETTERS 2008; 101:170403. [PMID: 18999725 DOI: 10.1103/physrevlett.101.170403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2008] [Indexed: 05/27/2023]
Abstract
We study a system of one-dimensional (iso)spin-1/2 bosons in the regime of strong repulsive interactions. We argue that the low-energy spectrum of the system consists of acoustic density waves and the spin excitations described by an effective ferromagnetic spin chain with a small exchange constant J. We use this description to compute the dynamic spin structure factor and the spectral functions of the system.
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Affiliation(s)
- K A Matveev
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, USA
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13
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Hew WK, Thomas KJ, Pepper M, Farrer I, Anderson D, Jones GAC, Ritchie DA. Spin-incoherent transport in quantum wires. PHYSICAL REVIEW LETTERS 2008; 101:036801. [PMID: 18764272 DOI: 10.1103/physrevlett.101.036801] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2007] [Indexed: 05/25/2023]
Abstract
When a quantum wire is weakly confined, a conductance plateau appears at e;{2}/h with decreasing carrier density in zero magnetic field accompanied by a gradual suppression of the 2e;{2}/h plateau. Applying an in-plane magnetic field B_{ parallel} does not alter the value of this quantization; however, the e;{2}/h plateau weakens with increasing B_{ parallel} up to 9 T, and then strengthens on further increasing B_{ parallel}, which also restores the 2e;{2}/h plateau. Our results are consistent with spin-incoherent transport in a one-dimensional wire.
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Affiliation(s)
- W K Hew
- Cavendish Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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14
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Zvonarev MB, Cheianov VV, Giamarchi T. Spin dynamics in a one-dimensional ferromagnetic bose gas. PHYSICAL REVIEW LETTERS 2007; 99:240404. [PMID: 18233427 DOI: 10.1103/physrevlett.99.240404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2007] [Indexed: 05/25/2023]
Abstract
We investigate the propagation of spin excitations in a one-dimensional ferromagnetic Bose gas. While the spectrum of longitudinal spin waves in this system is soundlike, the dispersion of transverse spin excitations is quadratic, making a direct application of the Luttinger liquid theory impossible. By using a combination of different analytic methods we derive the large time asymptotic behavior of the spin-spin dynamical correlation function for strong interparticle repulsion. The result has an unusual structure associated with a crossover from the regime of trapped spin wave to an open regime and does not have analogues in known low-energy universality classes of quantum 1D systems.
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Affiliation(s)
- M B Zvonarev
- DPMC-MaNEP, University of Geneva, 24 quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
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15
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Kindermann M. Tunneling exponents sensitive to impurity scattering in quantum wires. PHYSICAL REVIEW LETTERS 2007; 99:076801. [PMID: 17930913 DOI: 10.1103/physrevlett.99.076801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Indexed: 05/25/2023]
Abstract
We show that the scaling exponent for tunneling into a quantum wire in the "Coulomb Tonks gas" regime of impenetrable, but otherwise free, electrons is affected by impurity scattering in the wire. The exponent for tunneling into such a wire thus depends on the conductance through the wire. This striking effect originates from a many-body scattering resonance reminiscent of the Kondo effect. The predicted anomalous scaling is stable against weak perturbations of the ideal Tonks gas limit at sufficiently high energies, similar to the phenomenology of a quantum critical point.
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Affiliation(s)
- M Kindermann
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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16
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Syljuåsen OF. Length-dependent conductance of a spin-incoherent Hubbard chain: Monte Carlo calculations. PHYSICAL REVIEW LETTERS 2007; 98:166401. [PMID: 17501437 DOI: 10.1103/physrevlett.98.166401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2006] [Indexed: 05/15/2023]
Abstract
The dc conductance of a short spin-incoherent Hubbard chain coupled to leads is investigated using quantum Monte Carlo calculations. In contrast with the Luttinger liquid regime, where the conductance is equal to the noninteracting value, the spin-incoherent regime displays a conductance that decreases rapidly with chain length down to a value of roughly 1.5 e2/h for a four site chain followed by a slower decrease for longer chains. We also discuss the resistance contribution from scattering in the contacts.
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17
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Meyer JS, Matveev KA, Larkin AI. Transition from a one-dimensional to a quasi-one-dimensional state in interacting quantum wires. PHYSICAL REVIEW LETTERS 2007; 98:126404. [PMID: 17501141 DOI: 10.1103/physrevlett.98.126404] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Indexed: 05/15/2023]
Abstract
Upon increasing the electron density in a quantum wire, the one-dimensional electron system undergoes a transition to a quasi-one-dimensional state. In the absence of interactions between electrons, this corresponds to filling up the second subband of transverse quantization, and there are two gapless excitation modes above the transition. On the other hand, strongly interacting one-dimensional electrons form a Wigner crystal, and the transition corresponds to it splitting into two chains (zigzag crystal). We show that the soft mode driving the transition to the zigzag state is gapped, and only one gapless mode exists above the transition. Furthermore, we establish that in the vicinity of the transition already arbitrarily weak interactions open a gap in the second mode. We then argue that only one gapless mode exists near the transition at any interaction strength.
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Affiliation(s)
- Julia S Meyer
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
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18
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Matveev KA, Furusaki A, Glazman LI. Asymmetric zero-bias anomaly for strongly interacting electrons in one dimension. PHYSICAL REVIEW LETTERS 2007; 98:096403. [PMID: 17359182 DOI: 10.1103/physrevlett.98.096403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2006] [Indexed: 05/14/2023]
Abstract
We study a system of one-dimensional electrons in the regime of strong repulsive interactions, where the spin exchange coupling J is small compared with the Fermi energy, and the conventional Tomonaga-Luttinger theory does not apply. We show that the tunneling density of states has a form of an asymmetric peak centered near the Fermi level. In the spin-incoherent regime, where the temperature is large compared to J, the density of states falls off as a power law of energy epsilon measured from the Fermi level, with the prefactor at positive energies being twice as large as that at the negative ones. In contrast, at temperatures below J the density of states forms a split peak with most of the weight shifted to negative epsilon.
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Affiliation(s)
- K A Matveev
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
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19
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Fiete GA. Fermi-edge singularity in a spin-incoherent Luttinger liquid. PHYSICAL REVIEW LETTERS 2006; 97:256403. [PMID: 17280372 DOI: 10.1103/physrevlett.97.256403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2006] [Indexed: 05/13/2023]
Abstract
We theoretically investigate the Fermi-edge singularity in a spin-incoherent Luttinger liquid. Both cases of finite and infinite core hole mass are explored, as well as the effect of a static external magnetic field of arbitrary strength. For a finite mass core hole the absorption edge behaves as (omega-omega th)alpha/square root of absolute value (ln(omega-omega th)) for frequencies omega just above the threshold frequency omega th. The exponent alpha depends on the interaction parameter g of the interacting one dimensional system, the electron-hole coupling, and is independent of the magnetic field strength, the momentum, and the mass of the excited core hole (in contrast to the spin-coherent case). In the infinite mass limit, the spin-incoherent problem can be mapped onto an equivalent problem in a spinless Luttinger liquid for which the logarithmic factor is absent, and backscattering from the core hole leads to a universal contribution to the exponent alpha.
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Affiliation(s)
- Gregory A Fiete
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, California 93106, USA
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20
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Kindermann M, Brouwer PW, Millis AJ. Interference as a probe of spin incoherence in strongly interacting quantum wires. PHYSICAL REVIEW LETTERS 2006; 97:036809. [PMID: 16907534 DOI: 10.1103/physrevlett.97.036809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Indexed: 05/11/2023]
Abstract
We show that interference experiments can be used to identify the spin-incoherent regime of strongly interacting one-dimensional conductors. Two qualitative signatures of spin incoherence are found: a strong magnetic field dependence of the interference contrast and an anomalous scaling of the interference contrast with the applied voltage, with a temperature and magnetic field dependent scaling exponent. The experiments distinguish the spin-incoherent from the spin-polarized regime, and so may be useful in deciding between alternative explanations proposed for the anomalous conductance quantization observed in quantum point contacts and quantum wires at low density.
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Affiliation(s)
- M Kindermann
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca, New York 14853, USA
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21
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Auslaender OM, Steinberg H, Yacoby A, Tserkovnyak Y, Halperin BI, Baldwin KW, Pfeiffer LN, West KW. Spin-Charge Separation and Localization in One Dimension. Science 2005; 308:88-92. [PMID: 15802599 DOI: 10.1126/science.1107821] [Citation(s) in RCA: 320] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
We report on measurements of quantum many-body modes in ballistic wires and their dependence on Coulomb interactions, obtained by tunneling between two parallel wires in an GaAs/AlGaAs heterostructure while varying electron density. We observed two spin modes and one charge mode of the coupled wires and mapped the dispersion velocities of the modes down to a critical density, at which spontaneous localization was observed. Theoretical calculations of the charge velocity agree well with the data, although they also predict an additional charge mode that was not observed. The measured spin velocity was smaller than theoretically predicted.
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Affiliation(s)
- O M Auslaender
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel
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22
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Fiete GA, Balents L. Green's function for magnetically incoherent interacting electrons in one dimension. PHYSICAL REVIEW LETTERS 2004; 93:226401. [PMID: 15601105 DOI: 10.1103/physrevlett.93.226401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2004] [Indexed: 05/24/2023]
Abstract
Using a path integral approach and bosonization, we calculate the low-energy asymptotics of the one particle Green's function for a "magnetically incoherent" one dimensional strongly interacting electron gas at temperatures much greater than the typical exchange energy but much lower than the Fermi energy. The Green's function exhibits features reminiscent of spin-charge separation, with exponential spatial decay and scaling behavior with interaction dependent anomalous exponents inconsistent with any unitary conformal field theory. We compute the tunneling density of states at low energies and find that it is a power law in energy with exponent 1/(4g)-1, where g is the Luttinger interaction parameter in the charge sector. The underlying physics is made transparent by the simplicity of the approach. Our results generalize those of Cheianov and Zvonarev [Phys. Rev. Lett. 92, 176401 (2004)]].
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Affiliation(s)
- Gregory A Fiete
- Lyman Laboratory of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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