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During this reporting period, Dr. Lan and his research group have published a paper, in collaboration with the researchers at Nanyang Technological University Singapore, in Physical Review Letters (PHYSICAL REVIEW LETTERS 131, 193601 (2023)) on how to create a two-mode squeezed state with atomic mechanical oscillators. Two-mode squeezed states, which are entangled states with bipartite quantum correlations in continuous-variable systems, are essential for quantum information processing and metrology. Recently, significant progress has been made in continuous-variable quantum computing using the vibrational modes of trapped atoms, offering a high degree of control when hybridized with spin qubits. Creating two-mode squeezed states in such a platform could enable applications that, until now, have only been feasible with photons.

In this work, the research group demonstrate two-mode squeezed states by utilizing atoms in a two-dimensional optical lattice as quantum registers. These states are generated through a controlled projection based on the relative phase of two independent squeezed states. The individual squeezing is produced by sudden changes in the oscillators' frequencies, allowing for the generation of two-mode squeezed states at a rate within a fraction of the oscillation frequency. The states are validated using entanglement steering criteria and Fock state analysis. The results have potential applications in other mechanical oscillators for quantum sensing and continuous-variable quantum information processing.

Figure: Illustration of the preparation and measurement of single atom oscillators in two-dimensional (x–y plane) quantum registers. Each ball represents a single atom, with 5 μK, trapped in a two-dimensional optical harmonic potential formed by the lattice laser beams. The magnetic field B, optical pump, and depump laser pulses are used for the initialization of the atomic states. Colored thin arrows indicate the polarization of the optical beams. The Raman laser pulses are copropagating with the lattice beams and used for state characterization measurements. The figure is taken from Fig. 1(a) of PHYSICAL REVIEW LETTERS 131, 193601 (2023).