Minimally destructive, Doppler measurement of a quantized flow in a ring-shaped Bose–Einstein condensate

Abstract

The Doppler effect, the shift in the frequency of sound due to motion, is present in both classical gases and quantum superfluids. Here, we perform an insitu, minimally destructive measurement, of the persistent current in a ring-shaped, superfluid Bose-Einstein condensate using the Doppler effect. Phonon modes generated in this condensate have their frequencies Doppler shifted by a persistent current. This frequency shift will cause a standing-wave phonon mode to be "dragged" along with the persistent current. By measuring this precession, one can extract the background flow velocity. This technique will find utility in experiments where the winding number is important, such as in emerging 'atomtronic' devices.

Liquid Light with a Whirl

“…Note further that the results in Ref. [53] where the angular momentum of a ringshaped Bose-Einstein condensate was found by measuring the precession of density perturbations can also be interpreted in the language of synthetic magnetic fields: The precession can be understood as an effect of a constant magnetic field. We expect the photon fluid to behave correspondingly, which is highlighted by comparing in Fig.…”

Focus on atomtronics-enabled quantum technologies

“…• Minimally destructive, Doppler measurement of a quantized flow in a ring-shaped Bose-Einstein condensate, Kumar et al [31].…”

Non-spreading matter-wave packets in a ring

“…Due to potential applications in realizing matter-wave Sagnac interferometer [36,37,38,39,40], atomic analogy of SQUID circuits [41,42,43], persistent current [44,45,46,47] and quantum time crystal [48,49,50], non-spreading matter-wave packets in a ring also deserve considerable research interests. Now the point is that, we are inquisitive about whether non-spreading wave packets can exist in a free ring.…”