Ultracold molecules for quantum simulation: rotational coherences in CaF and RbCs

Journal article

Polar molecules offer a new platform for quantum simulation of systems with long-range interactions, based on the electrostatic interaction between their electric dipole moments. Here, we report the development of coherent quantum state control using microwave fields in $^{40}$Ca$^{19}$F and $^{87}$Rb$^{133}$Cs molecules, a crucial ingredient for many quantum simulation applications. We perform Ramsey interferometry measurements with fringe spacings of $\sim 1~\rm kHz$ and investigate the dephasing time of a superposition of $N=0$ and $N=1$ rotational states when the molecules are confined. For both molecules, we show that a judicious choice of molecular hyperfine states minimises the impact of spatially varying transition-frequency shifts across the trap. For magnetically trapped $^{40}$Ca$^{19}$F we use a magnetically insensitive transition and observe a coherence time of 0.61(3)~ms. For optically trapped $^{87}$Rb$^{133}$Cs we exploit an avoided crossing in the AC Stark shifts and observe a maximum coherence time of 0.75(6)~ms.

Authors: Blackmore, JA; Caldwell, L; Gregory, PD; Bridge, EM; Sawant, R

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: IOP Publishing
• Journal: Quantum Science and Technology
• Volume: 4
• Issue: 1
• Article number: 014010
• Publication date: 2018-11-05
• Acceptance date: 2018-11-05
• DOI: 10.1088/2058-9565/aaee35
• ISSN: 2058-9565
• Language: English
• Keywords: Ramsey; coherence; CaF; RbCs; quantum simulation; ultracold molecules