Physics – Quantum Physics
Scientific paper
2006-12-15
New J. Phys 9, 156 (2007)
Physics
Quantum Physics
Scientific paper
10.1088/1367-2630/9/5/156
We analyze a quantum mechanical gyroscope which is modeled as a large spin and used as a reference against which to measure the angular momenta of spin-1/2 particles. These measurements induce a back-action on the reference which is the central focus of our study. We begin by deriving explicit expressions for the quantum channel representing the back-action. Then, we analyze the dynamics incurred by the reference when it is used to sequentially measure particles drawn from a fixed ensemble. We prove that the reference thermalizes with the measured particles and find that generically, the thermal state is reached in time which scales linearly with the size of the reference. This contrasts a recent conclusion of Bartlett et al. that this takes a quadratic amount of time when the particles are completely unpolarized. We now understand their result in terms of a simple physical principle based on symmetries and conservation laws. Finally, we initiate the study of the non-equilibrium dynamics of the reference. Here we find that a reference in a coherent state will essentially remain in one when measuring polarized particles, while rotating itself to ultimately align with the polarization of the particles.
Poulin David
Yard Jon
No associations
LandOfFree
Dynamics of a Quantum Reference Frame does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Dynamics of a Quantum Reference Frame, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Dynamics of a Quantum Reference Frame will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-133099