TY - JOUR

T1 - Quantum optics with quantum gases

T2 - Controlled state reduction by designed light scattering

AU - Mekhov, Igor B.

AU - Ritsch, Helmut

N1 - Copyright: Copyright 2009 Elsevier B.V., All rights reserved.

PY - 2009/8/6

Y1 - 2009/8/6

N2 - Cavity-enhanced light scattering from an ultracold gas in an optical lattice constitutes a quantum measurement with a controllable form of the measurement backaction. Time-resolved counting of scattered photons alters the state of the atoms without particle loss implementing a quantum nondemolition measurement. The conditional dynamics is given by the interplay between photodetection events (quantum jumps) and no-count processes. The class of emerging atomic many-body states can be chosen via the optical geometry and light frequencies. Light detection along the angle of a diffraction maximum (Bragg angle) creates an atom-number-squeezed state, while light detection at diffraction minima leads to the macroscopic superposition states (Schrödinger cat states) of different atom numbers in the cavity mode. A measurement of the cavity transmission intensity can lead to atom-number-squeezed or macroscopic superposition states depending on its outcome. We analyze the robustness of the superposition with respect to missed counts and find that a transmission measurement yields more robust and controllable superposition states than the ones obtained by scattering at a diffraction minimum.

AB - Cavity-enhanced light scattering from an ultracold gas in an optical lattice constitutes a quantum measurement with a controllable form of the measurement backaction. Time-resolved counting of scattered photons alters the state of the atoms without particle loss implementing a quantum nondemolition measurement. The conditional dynamics is given by the interplay between photodetection events (quantum jumps) and no-count processes. The class of emerging atomic many-body states can be chosen via the optical geometry and light frequencies. Light detection along the angle of a diffraction maximum (Bragg angle) creates an atom-number-squeezed state, while light detection at diffraction minima leads to the macroscopic superposition states (Schrödinger cat states) of different atom numbers in the cavity mode. A measurement of the cavity transmission intensity can lead to atom-number-squeezed or macroscopic superposition states depending on its outcome. We analyze the robustness of the superposition with respect to missed counts and find that a transmission measurement yields more robust and controllable superposition states than the ones obtained by scattering at a diffraction minimum.

UR - http://www.scopus.com/inward/record.url?scp=68549083659&partnerID=8YFLogxK

U2 - 10.1103/PhysRevA.80.013604

DO - 10.1103/PhysRevA.80.013604

M3 - Article

AN - SCOPUS:68549083659

VL - 80

JO - Physical Review A - Atomic, Molecular, and Optical Physics

JF - Physical Review A - Atomic, Molecular, and Optical Physics

SN - 1050-2947

IS - 1

M1 - 013604

ER -