Observation of Atom Number Fluctuations in a Bose-Einstein Condensate

TY - JOUR

T1 - Observation of Atom Number Fluctuations in a Bose-Einstein Condensate

AU - Kristensen, M. A.

AU - Christensen, M. B.

AU - Gajdacz, M.

AU - Iglicki, M.

AU - Pawowski, K.

AU - Klempt, Carsten

AU - Sherson, J. F.

AU - Rzążewski, K.

AU - Hilliard, A. J.

AU - Arlt, J. J.

PY - 2019/4

Y1 - 2019/4

N2 - Fluctuations are a key property of both classical and quantum systems. While the fluctuations are well understood for many quantum systems at zero temperature, the case of an interacting quantum system at finite temperature still poses numerous challenges. Despite intense theoretical investigations of atom number fluctuations in Bose-Einstein condensates, their amplitude in experimentally relevant interacting systems is still not fully understood. Moreover, technical limitations have prevented their experimental investigation to date. Here we report the observation of these fluctuations. Our experiments are based on a stabilization technique, which allows for the preparation of ultracold thermal clouds at the shot noise level, thereby eliminating numerous technical noise sources. Furthermore, we make use of the correlations established by the evaporative cooling process to precisely determine the fluctuations and the sample temperature. This allows us to observe a telltale signature: the sudden increase in fluctuations of the condensate atom number close to the critical temperature.

AB - Fluctuations are a key property of both classical and quantum systems. While the fluctuations are well understood for many quantum systems at zero temperature, the case of an interacting quantum system at finite temperature still poses numerous challenges. Despite intense theoretical investigations of atom number fluctuations in Bose-Einstein condensates, their amplitude in experimentally relevant interacting systems is still not fully understood. Moreover, technical limitations have prevented their experimental investigation to date. Here we report the observation of these fluctuations. Our experiments are based on a stabilization technique, which allows for the preparation of ultracold thermal clouds at the shot noise level, thereby eliminating numerous technical noise sources. Furthermore, we make use of the correlations established by the evaporative cooling process to precisely determine the fluctuations and the sample temperature. This allows us to observe a telltale signature: the sudden increase in fluctuations of the condensate atom number close to the critical temperature.

KW - ANOMALOUS FLUCTUATIONS

KW - BOSONS

KW - CRITICAL-TEMPERATURE

KW - GAS

KW - IDEAL

UR - https://arxiv.org/abs/1812.03064

U2 - 10.1103/PhysRevLett.122.163601

DO - 10.1103/PhysRevLett.122.163601

M3 - Journal article

C2 - 31075024

SN - 0031-9007

VL - 122

JO - Physical Review Letters

JF - Physical Review Letters

M1 - 163601

ER -