Nondestructive microwave detection of a coherent quantum dynamics in cold atoms

Abstract

Cold atom quantum sensors based on atom interferometry are among the most accurate instruments used in fundamental physics, metrology, and foreseen for autonomous inertial navigation. However, they typically have optically complex, cumbersome, and low-bandwidth atom detection systems, limiting their practical applications. Here, we demonstrate an enabling technology for high-bandwidth, compact, and nondestructive detection of cold atoms, using microwave radiation. We measure the reflected microwave signal to coherently and distinctly detect the population of single quantum states with a bandwidth close to 30 kHz and a design destructivity that we set to 0.04%. We use a horn antenna and free-falling molasses cooled atoms in order to demonstrate the feasibility of this technique in conventional cold atom interferometers. This technology, combined with coplanar waveguides used as microwave sources, provides a basic design building block for detection in future atom chip-based compact quantum inertial sensors.

A quantum register using collective excitations in a Bose-Einstein condensate

“…There are several methods to nondestructively detect population oscillations in a BEC. It was shown in [34] that Rabi oscillations between |0〉 and |2〉 in 87 Rb atoms may be observed by measuring the MW impedance of the atoms. In [37], BEC atoms coherently exchanged photons with two optical beams, and the resulting intensity fluctuations in the beams were observed on a CCD camera.…”

“…Researchers have also considered realizing cold atom qubits using Bose-Einstein condensates (BECs) [29][30][31][32][33], and these proposals are often analogous to different types of superconducting Josephson junction qubits. Although these platforms may be less scalable and suffer from longer gate times compared to lattice-based approaches, it can be easier to read out their states without using resonant light because BECs are mesoscopic objects [34][35][36][37][38]. Additionally, it can be easier to couple BECs (rather than single atoms) to photonic flying qubits [39].…”

Realizing a quantum register using collective excitations in an atomic ensemble without a Rydberg blockade

“…There are several methods to nondestructively detect population oscillations in a BEC. It was shown in [30] that Rabi oscillations between the two m F = 0 levels in 87 Rb atoms may be observed by measuring the MW impedance of the atoms. In Ref [33], BEC atoms coherently exchanged photons with two optical beams, and the resulting intensity fluctuations in the beams were observed on a CCD camera.…”

“…Researchers have also considered realizing cold atom qubits using Bose-Einstein condensates (BECs) [25][26][27][28][29], often analogously to their superconducting Josephson junction counterparts. Although these platforms may be less scalable and suffer from longer gate times compared to lattice-based approaches, it can be easier to read out their states without using resonant light because BECs are mesoscopic objects [30][31][32][33][34]. Additionally, it can be easier to couple BECs (rather than single atoms) to photonic flying qubits [35].…”