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Quantum entanglement between an atom and a molecule



Yiheng Lin, David Leibrandt, Dietrich Leibfried, Chin-wen Chou


Expanding quantum control to a broad range of physical systems paves the way for advances in various aspects of science and technology, such as stringent tests of fundamental physics, quantum-enhanced sensors, and quantum information processing. Conventional information processors freely convert information between different physical representations to process, store, or transmit information and it seems plausible that quantum information should be convertible between different physical entities as well when scaling up quantum systems toward real-world applications. Quantum controlled molecules in particular can transduce quantum information across a wide range of qubit frequencies, from a few kHz for transitions within the same rotational manifold,1 a few GHz in hyper ne transitions, a few THz in rotational transitions, to hundreds of THz in fundamental and overtone vibrational transitions, possibly within the same molecule. Here, we report entanglement between internal states of a 40Ca+ atomic ion and states of the rotation of a 40CaH+ molecular ion. The qubit addressed in the molecule has a frequency of either 13.4 kHz or 855 GHz, showing the versatility of transitions that can be utilized in molecules for cross-platform qubit interconnection. This work demonstrates how molecules, encompassing a vast selection of accessible qubit frequencies, can become mediators between frequency-incompatible qubits to enable hybrid quantum systems. We anticipate that quantum control and measurement on molecules as demonstrated here will create opportunities for quantum information science, fundamental and applied physics, and controlled quantum chemistry.


quantum control, entanglement, molecule


Lin, Y. , Leibrandt, D. , Leibfried, D. and Chou, C. (2020), Quantum entanglement between an atom and a molecule, Nature, [online], (Accessed March 21, 2023)
Created May 20, 2020, Updated October 12, 2021