Second-Scale Nuclear Spin Coherence Time of Trapped Ultracold $^{23}$Na$^{40}$K Molecules

TL;DR

This paper demonstrates that ultracold NaK molecules exhibit nuclear spin coherence times of about one second, enabling potential applications in quantum memory and quantum information processing with long coherence durations.

Contribution

It reports the first observation of long-lived nuclear spin coherence in ultracold NaK molecules, with coherence times suitable for quantum memory and processing.

Findings

Coherence times of approximately one second observed.

Ramsey spectroscopy used to measure nuclear spin coherence.

Potential for 10,000 quantum gate operations within coherence time.

Abstract

Coherence, the stability of the relative phase between quantum states, lies at the heart of quantum mechanics. Applications such as precision measurement, interferometry, and quantum computation are enabled by physical systems that have quantum states with robust coherence. With the creation of molecular ensembles at sub-$\mu$K temperatures, diatomic molecules have become a novel system under full quantum control. Here, we report on the observation of stable coherence between a pair of nuclear spin states of ultracold fermionic NaK molecules in the singlet rovibrational ground state. Employing microwave fields, we perform Ramsey spectroscopy and observe coherence times on the scale of one second. This work opens the door for the exploration of single molecules as a versatile quantum memory. Switchable long-range interactions between dipolar molecules can further enable two-qubit gates, allowing quantum storage and processing in the same physical system. Within the observed coherence time, $10^4$ one- and two-qubit gate operations will be feasible.