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Park AJ, Picard LRB, Patenotte GE, Zhang JT, Rosenband T, Ni KK. Extended Rotational Coherence of Polar Molecules in an Elliptically Polarized Trap. PHYSICAL REVIEW LETTERS 2023; 131:183401. [PMID: 37977633 DOI: 10.1103/physrevlett.131.183401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2023] [Revised: 09/02/2023] [Accepted: 09/25/2023] [Indexed: 11/19/2023]
Abstract
We demonstrate long rotational coherence of individual polar molecules in the motional ground state of an optical trap. In the present, previously unexplored regime, the rotational eigenstates of molecules are dominantly quantized by trapping light rather than static fields, and the main source of decoherence is differential light shift. In an optical tweezer array of NaCs molecules, we achieve a three-orders-of-magnitude reduction in differential light shift by changing the trap's polarization from linear to a specific "magic" ellipticity. With spin-echo pulses, we measure a rotational coherence time of 62(3) ms (one pulse) and 250(40) ms (up to 72 pulses), surpassing the projected duration of resonant dipole-dipole entangling gates by orders of magnitude.
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Affiliation(s)
- Annie J Park
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Lewis R B Picard
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Gabriel E Patenotte
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Jessie T Zhang
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | | | - Kang-Kuen Ni
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
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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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Tscherbul TV, Ye J, Rey AM. Robust Nuclear Spin Entanglement via Dipolar Interactions in Polar Molecules. PHYSICAL REVIEW LETTERS 2023; 130:143002. [PMID: 37084438 DOI: 10.1103/physrevlett.130.143002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2022] [Accepted: 03/13/2023] [Indexed: 05/03/2023]
Abstract
We propose a general protocol for on-demand generation of robust entangled states of nuclear and/or electron spins of ultracold ^{1}Σ and ^{2}Σ polar molecules using electric dipolar interactions. By encoding a spin-1/2 degree of freedom in a combined set of spin and rotational molecular levels, we theoretically demonstrate the emergence of effective spin-spin interactions of the Ising and XXZ forms, enabled by efficient magnetic control over electric dipolar interactions. We show how to use these interactions to create long-lived cluster and squeezed spin states.
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Affiliation(s)
- Timur V Tscherbul
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - Jun Ye
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ana Maria Rey
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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Christakis L, Rosenberg JS, Raj R, Chi S, Morningstar A, Huse DA, Yan ZZ, Bakr WS. Probing site-resolved correlations in a spin system of ultracold molecules. Nature 2023; 614:64-69. [PMID: 36725998 DOI: 10.1038/s41586-022-05558-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 11/11/2022] [Indexed: 02/03/2023]
Abstract
Synthetic quantum systems with interacting constituents play an important role in quantum information processing and in explaining fundamental phenomena in many-body physics. Following impressive advances in cooling and trapping techniques, ensembles of ultracold polar molecules have emerged as a promising platform that combines several advantageous properties1-11. These include a large set of internal states with long coherence times12-17 and long-range, anisotropic interactions. These features could enable the exploration of intriguing phases of correlated quantum matter, such as topological superfluids18, quantum spin liquids19, fractional Chern insulators20 and quantum magnets21,22. Probing correlations in these phases is crucial to understanding their properties, necessitating the development of new experimental techniques. Here we use quantum gas microscopy23 to measure the site-resolved dynamics of quantum correlations of polar 23Na87Rb molecules confined in a two-dimensional optical lattice. By using two rotational states of the molecules, we realize a spin-1/2 system with dipolar interactions between particles, producing a quantum spin-exchange model21,22,24,25. We study the evolution of correlations during the thermalization process of an out-of-equilibrium spin system for both spatially isotropic and anisotropic interactions. Furthermore, we examine the correlation dynamics of a spin-anisotropic Heisenberg model engineered from the native spin-exchange model by using periodic microwave pulses26-28. These experiments push the frontier of probing and controlling interacting systems of ultracold molecules, with prospects for exploring new regimes of quantum matter and characterizing entangled states that are useful for quantum computation29,30 and metrology31.
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Affiliation(s)
| | | | - Ravin Raj
- Department of Physics, Princeton University, Princeton, NJ, USA
| | - Sungjae Chi
- Department of Physics, Princeton University, Princeton, NJ, USA
| | | | - David A Huse
- Department of Physics, Princeton University, Princeton, NJ, USA
| | - Zoe Z Yan
- Department of Physics, Princeton University, Princeton, NJ, USA
| | - Waseem S Bakr
- Department of Physics, Princeton University, Princeton, NJ, USA.
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