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Le Duc V, Zou J, Osterwalder A. Alignment of ND3 molecules in dc-electric fields. J Chem Phys 2024; 160:204305. [PMID: 38804496 DOI: 10.1063/5.0210431] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2024] [Accepted: 05/08/2024] [Indexed: 05/29/2024] Open
Abstract
The control of movement and orientation of gas-phase molecules has become the focus of many research areas in molecular physics. Here, ND3 molecules are polarized in a segmented, curved electrostatic guide and adiabatically aligned inside a rotatable mass spectrometer (MS). Alignment is probed by photoionization using a linearly polarized laser. Rotation of the polarization at fixed MS orientation has the same effect as the rotation of the MS at fixed polarization, proving that the molecular alignment adiabatically follows the MS axis. Polarization-dependent ion signals reveal state-specific populations and allow for a quantification of the aligned sample in the space-fixed reference frame.
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Affiliation(s)
- Viet Le Duc
- Institute for Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Junwen Zou
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - Andreas Osterwalder
- Institute for Chemical Sciences and Engineering (ISIC), Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
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Zhang ZY, Sun Z, Duan T, Ding YK, Huang X, Liu JM. Entanglement Generation of Polar Molecules via Deep Reinforcement Learning. J Chem Theory Comput 2024; 20:1811-1820. [PMID: 38320113 DOI: 10.1021/acs.jctc.3c01214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2024]
Abstract
Polar molecules are a promising platform for achieving scalable quantum information processing because of their long-range electric dipole-dipole interactions. Here, we take the coupled ultracold CaF molecules in an external electric field with gradient as qubits and concentrate on the creation of intermolecular entanglement with the method of deep reinforcement learning (RL). After sufficient training episodes, the educated RL agents can discover optimal time-dependent control fields that steer the molecular systems from separate states to two-qubit and three-qubit entangled states with high fidelities. We analyze the fidelities and the negativities (characterizing entanglement) of the generated states as a function of training episodes. Moreover, we present the population dynamics of the molecular systems under the influence of control fields discovered by the agents. Compared with the schemes for creating molecular entangled states based on optimal control theory, some conditions (e.g., molecular spacing and electric field gradient) adopted in this work are more feasible in the experiment. Our results demonstrate the potential of machine learning to effectively solve quantum control problems in polar molecular systems.
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Affiliation(s)
- Zuo-Yuan Zhang
- School of Physical Science and Technology, Yangzhou University, Yangzhou 225009, China
| | - Zhaoxi Sun
- Changping Laboratory, Beijing 102206, China
| | - Tao Duan
- State Key Laboratory of Transient Optics and Photonics, Xi'an Institute of Optics and Precision Mechanics of CAS, Xi'an 710119, China
| | - Yi-Kai Ding
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
| | - Xinning Huang
- School of Physical Science and Technology, Yangzhou University, Yangzhou 225009, China
| | - Jin-Ming Liu
- State Key Laboratory of Precision Spectroscopy, School of Physics and Electronic Science, East China Normal University, Shanghai 200241, China
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Zhang C, Yu P, Jadbabaie A, Hutzler NR. Quantum-Enhanced Metrology for Molecular Symmetry Violation Using Decoherence-Free Subspaces. PHYSICAL REVIEW LETTERS 2023; 131:193602. [PMID: 38000409 DOI: 10.1103/physrevlett.131.193602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 10/12/2023] [Indexed: 11/26/2023]
Abstract
We propose a method to measure time-reversal symmetry violation in molecules that overcomes the standard quantum limit while leveraging decoherence-free subspaces to mitigate sensitivity to classical noise. The protocol does not require an external electric field, and the entangled states have no first-order sensitivity to static electromagnetic fields as they involve superpositions with zero average lab-frame projection of spins and dipoles. This protocol can be applied with trapped neutral or ionic species, and can be implemented using methods that have been demonstrated experimentally.
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Affiliation(s)
- Chi Zhang
- California Institute of Technology, Division of Physics, Mathematics, and Astronomy, Pasadena, California 91125, USA
| | - Phelan Yu
- California Institute of Technology, Division of Physics, Mathematics, and Astronomy, Pasadena, California 91125, USA
| | - Arian Jadbabaie
- California Institute of Technology, Division of Physics, Mathematics, and Astronomy, Pasadena, California 91125, USA
| | - Nicholas R Hutzler
- California Institute of Technology, Division of Physics, Mathematics, and Astronomy, Pasadena, California 91125, USA
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Franke J, Muleady SR, Kaubruegger R, Kranzl F, Blatt R, Rey AM, Joshi MK, Roos CF. Quantum-enhanced sensing on optical transitions through finite-range interactions. Nature 2023; 621:740-745. [PMID: 37648868 DOI: 10.1038/s41586-023-06472-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2023] [Accepted: 07/21/2023] [Indexed: 09/01/2023]
Abstract
The control over quantum states in atomic systems has led to the most precise optical atomic clocks so far1-3. Their sensitivity is bounded at present by the standard quantum limit, a fundamental floor set by quantum mechanics for uncorrelated particles, which can-nevertheless-be overcome when operated with entangled particles. Yet demonstrating a quantum advantage in real-world sensors is extremely challenging. Here we illustrate a pathway for harnessing large-scale entanglement in an optical transition using 1D chains of up to 51 ions with interactions that decay as a power-law function of the ion separation. We show that our sensor can emulate many features of the one-axis-twisting (OAT) model, an iconic, fully connected model known to generate scalable squeezing4 and Greenberger-Horne-Zeilinger-like states5-8. The collective nature of the state manifests itself in the preservation of the total transverse magnetization, the reduced growth of the structure factor, that is, spin-wave excitations (SWE), at finite momenta, the generation of spin squeezing comparable with OAT (a Wineland parameter9,10 of -3.9 ± 0.3 dB for only N = 12 ions) and the development of non-Gaussian states in the form of multi-headed cat states in the Q-distribution. We demonstrate the metrological utility of the states in a Ramsey-type interferometer, in which we reduce the measurement uncertainty by -3.2 ± 0.5 dB below the standard quantum limit for N = 51 ions.
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Affiliation(s)
- Johannes Franke
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
| | - Sean R Muleady
- JILA, NIST and Department of Physics, University of Colorado, Boulder, CO, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO, USA
| | - Raphael Kaubruegger
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
- Institut für Theoretische Physik, Universität Innsbruck, Innsbruck, Austria
| | - Florian Kranzl
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
| | - Rainer Blatt
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
| | - Ana Maria Rey
- JILA, NIST and Department of Physics, University of Colorado, Boulder, CO, USA.
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO, USA.
| | - Manoj K Joshi
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria
| | - Christian F Roos
- Institut für Experimentalphysik, Universität Innsbruck, Innsbruck, Austria.
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Innsbruck, Austria.
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Asnaashari K, Krems RV, Tscherbul TV. General Classification of Qubit Encodings in Ultracold Diatomic Molecules. J Phys Chem A 2023; 127:6593-6602. [PMID: 37494464 DOI: 10.1021/acs.jpca.3c02835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Owing to their rich internal structure and significant long-range interactions, ultracold molecules have been widely explored as carriers of quantum information. Several different schemes for encoding qubits into molecular states, both bare and field-dressed, have been proposed. At the same time, the rich internal structure of molecules leaves many unexplored possibilities for qubit encodings. We show that all molecular qubit encodings can be classified into four classes by the type of the effective interaction between the qubits. In the case of polar molecules, the four classes are determined by the relative magnitudes of matrix elements of the dipole moment operator in the single-molecule basis. We exemplify our classification scheme by considering the encoding of the effective spin-1/2 system into nonadjacent rotational states (e.g., N = 0 and 2) of polar and nonpolar molecules with the same nuclear spin projection. Our classification scheme is designed to inform the optimal choice of molecular qubit encoding for quantum information storage and processing applications, as well as for dynamical generation of many-body entangled states and for quantum annealing.
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Affiliation(s)
- Kasra Asnaashari
- Department of Chemistry, University of British Columbia, Vancouver V6T 1Z1, Canada
| | - Roman V Krems
- Department of Chemistry, University of British Columbia, Vancouver V6T 1Z1, Canada
| | - Timur V Tscherbul
- Department of Physics, University of Nevada, Reno, Nevada 89557, United States
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