Rotational Coherence Times of Polar Molecules in Optical Tweezers

Abstract

Qubit coherence times are critical to the performance of any robust quantum computing platform. For quantum information processing using arrays of polar molecules, a key performance parameter is the molecular rotational coherence time. We report a 93(7) ms coherence time for rotational state qubits of laser cooled CaF molecules in optical tweezer traps, over an order of magnitude longer than previous systems. Inhomogeneous broadening due to the differential polarizability between the qubit states is suppressed by tuning the tweezer polarization and applied magnetic field to a "magic" angle. The coherence time is limited by the residual differential polarizability, implying improvement with further cooling. A single spin-echo pulse is able to extend the coherence time to nearly half a second. The measured coherence times demonstrate the potential of polar molecules as high fidelity qubits.

Enriching the quantum toolbox of ultracold molecules with Rydberg atoms

“…While the Rydberg atom decay limits the fidelity when compared to a purely molecular system, this scheme preserves the benefits of storing information in molecules. This includes relatively long coherence times [8][9][10][11], and access to a large number of internal states to selectively interact molecules in a larger array. These internal states can also be used as qudits [57] or as lattice sites in a synthetic dimension [58].…”

“…Individually trapped ultracold polar molecules [1][2][3][4][5][6][7] have emerged as a promising candidate system for scalable quantum computing due to their long-lived internal states and intrinsic tunable interactions. Long coherence times have been demonstrated for many molecular degrees of freedom, including nuclear spin [8,9], rotation [10][11][12], and vibration [13]. Molecular-frame dipole moments allow molecules to interact via the dipolar interaction, which has been observed for molecular gases prepared in opposite parity rotational states [14,15].…”

Narrow-line imaging of single strontium atoms in shallow optical tweezers

“…Optical tweezers have emerged as a powerful tool for quantum applications. They enable state of the art quantum simulation and computation [1][2][3][4], high fidelity and long coherence time qubits [5][6][7][8], quantum metrology [9][10][11], quantum chemistry [12,13], among numerous other applications. Optical tweezers with alkaline-earth(-like) atoms, in particular with strontium and ytterbium, have been recently realized, offering new possibilities in expanding these applications [14][15][16].…”

An Electro-Optical Trap for Polar Molecules

“…Among the recently demonstrated advantages of optical traps (or of optical tweezers, their variant that makes use of tight, diffraction-limited focusing of the optical field) are long coherence times of the trapped samples 8 . These are key to such applications as searches for physics beyond the Standard Model 9 and quantum computing and quantum simulation [10][11][12] .…”