Cold atoms near superconductors: atomic spin coherence beyond the Johnson noise limit

Abstract

Abstract. We report on the measurement of atomic spin coherence near the surface of a superconducting niobium wire. As compared to normal conducting metal surfaces, the atomic spin coherence is maintained for time periods beyond the Johnson noise limit. The result provides experimental evidence that magnetic near-field noise near the superconductor is strongly suppressed. Such long atomic spin coherence times near superconductors open the way towards the development of coherently coupled cold atom/solid state hybrid quantum systems with potential applications in quantum information processing and precision force sensing.

Heating rate and spin flip lifetime due to near-field noise in layered superconducting atom chips

“…Similarly to the niobium-based chip structures, the spin flip lifetime close to the YBCO+gold structure is shorter than the one obtained near the bare superconductor, however the difference is less than an order of magnitude. A complete accounting of the total lifetime must include other experimental restrictions, such as collisions with background gas [11].…”

“…The reduction of the spin flip rate has been shown experimentally for different chip types: with and without a gold layer above the superconductor [10][11][12][13]. The purpose of the top gold layer in atom chips is to use them in mirror-MOTs [26].…”

“…In the area of magnetic trapping of ultracold atoms, considerable attention has been recently devoted to the interaction of atomic clouds with the surfaces of both superconducting atom chips [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] and superconducting solid state devices [17][18][19][20]. Technological advances will allow a new generation of fundamental experiments and applications involving the control of the interface between atomic systems and quantum solid state devices.…”

Trapping of ultracold atoms in a 3He/4He dilution refrigerator

“…Several groups are currently preparing cold atomic clouds in the vicinity of superconducting chips at 77 K, cooled by liquid nitrogen, and at 4 K, cooled by liquid 4 He [11][12][13][14][15][16][17][18][19][20][21][22][23]. The vision of quantum state transfer between superconducting circuits and cold atoms requires further experimental development, in particular the preparation of atomic clouds close to millikelvin surfaces.…”

Programmable trap geometries with superconducting atom chips

“…One demonstrated advantage of superconductors over conventional conductors is the significant reduction of near-field noise in current-carrying structures leading to low atomic heating rates and enhanced spin-flip lifetimes [9][10][11][12][13][14]. Proposals in this area advocate experimental designs for coherent coupling with atomic or molecular quantum systems that exploit the distinct properties of superconductors [15][16][17][18][19][20][21][22].…”