Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session C03: Molecular QubitsInvited Live Streamed
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Chair: David Leibrandt, UCLA Room: Ballroom 111 B |
Tuesday, June 6, 2023 10:45AM - 11:15AM |
C03.00001: Measuring quantum correlations in a many-body system of polar molecules Invited Speaker: Waseem S Bakr Ultracold molecules have promising applications in the fields of quantum computing, simulation of many-body systems, fundamental precision measurements, and state-controlled chemistry. There has been rapid experimental progress in our ability to prepare and manipulate ultracold molecular gases, either by assembling them in-situ from atomic quantum gases or by direct laser cooling of special molecular species. An outstanding challenge in the field is the detection of quantum correlations between molecules. We have recently developed a novel apparatus for imaging single diatomic molecules in an ultracold gas prepared in well-defined electronic, rovibrational and hyperfine states. I will describe how we used this capability to measure quantum correlations due to the quantum statistics of the molecules or due to entanglement mediated by dipolar interactions. As an example of a potential application, I will discuss our study of out-of-equilibrium dynamics in tunable quantum spin models and our measurements of the evolution of spatial correlations during the ensuing thermalization process. |
Tuesday, June 6, 2023 11:15AM - 11:45AM |
C03.00002: Optical tweezer arrays of molecules from the bottom-up for quantum science Invited Speaker: Jessie T Zhang Ultracold molecules offer rich internal states and tunable long-range interactions that render them favorable for a wide range of quantum science applications. Towards this end, individual particle control over single molecules with long coherence times are desirable. In this talk, I will discuss our platform of molecular qubits, where optical tweezer arrays of NaCs molecules are created starting from individual Na and Cs atoms. This approach allows fine control over individual molecules, whilst also assuring molecules are in their internal and external ground states. Compared to other molecular qubit systems, NaCs has an exceptionally large differential light shift between qubit states under normal trapping conditions that cannot be eliminated by established methods using external DC magnetic fields. In our system, we gain control over the differential light shift by tuning the ellipticity of the polarization of the trapping light. In particular, by tuning to a magic ellipticity, we achieve up to three orders of magnitude decrease in the differential light shift between two specific rotational levels, and improve the rotational coherence time by two orders of magnitude. Along with dipolar interactions between individual molecules, this sets the stage for many opportunities in quantum computing and quantum simulation in our platform. |
Tuesday, June 6, 2023 11:45AM - 12:15PM |
C03.00003: Dipolar spin-exchange and entanglement between molecules in an optical tweezer array Invited Speaker: Yicheng Bao Due to their intrinsic electric dipole moments and rich internal structure, ultracold polar molecules are promising candidate qubits for quantum computing and quantum simulations. Their long-lived molecular rotational states form robust qubits while the long-range dipolar interaction between molecules provides quantum entanglement. Using a molecular optical tweezer array, single molecules can be moved and separately addressed using optical and microwave fields. In this talk, I will discuss our recent work on demonstration of dipolar spin-exchange interactions between single CaF molecules trapped in an optical tweezer array. We realize the spin-$frac{1}{2}$ quantum XY model by encoding an effective spin-$frac{1}{2}$ system into the rotational states of the molecules, and use it to demonstrate a two-qubit (two-molecule) quantum gate. Conditioned on the verified existence of molecules in both tweezers at the end of the measurement, we obtain a Bell state fidelity of 0.87(6). Employing interleaved tweezer arrays, we demonstrate high fidelity single site molecular addressability. |
Tuesday, June 6, 2023 12:15PM - 12:45PM |
C03.00004: Host-matrix control for improving spin coherence in molecular color centers Invited Speaker: Sam L Bayliss Molecular color centers seek to achieve core functionality of solid-state color centers within a chemically synthesizable molecule [1]. Using a molecular architecture for color centers provides several opportunities to favorably tune their properties, for example, by modifying their host environment. Here we demonstrate how host-matrix control can be used to enhance chromium(IV)-based molecular color centers. We show that inserting these molecules into a non-isostructural host matrix significantly enhances their spin coherence compared to using an isostructural host. This behavior arises from a breaking of the qubit’s symmetry due to the host-matrix, which generates a significant transverse zero-field splitting and creates clock transitions which are insensitive to magnetic-field noise. We find close agreement between our experimental results and first-principles cluster-correlation expansion simulations, and further experimentally demonstrate enhanced optical contrast and spin-lattice relaxation times for host-matrix engineered molecular color centers. These results highlight the modularity and tunability of molecular color centers, indicating their promise for applications such as quantum sensing. |
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