#### Document Type

Article

#### Publication Date

2017

#### Abstract

We examine the time reversal symmetry of quantum measurement sequences by introducing a forward and backward Janus sequence of measurements. If the forward sequence of measurements creates a sequence of quantum states in time, starting from an initial state and ending in a final state, then the backward sequence begins with the time-reversed final state, exactly retraces the intermediate states, and ends with the time-reversed initial state. We prove that such a sequence can always be constructed, showing that unless the measurements are ideal projections, it is impossible to tell if a given sequence of measurements is progressing forward or backward in time. A statistical arrow of time emerges only because typically the forward sequence is more probable than the backward sequence.

#### Recommended Citation

Jordan, A.N., Chantasri, A., Murch, K., Dressel, J., Korotkov, A.N., 2017. Janus sequences of quantum measurements and the arrow of time. *AIP Conference Proceedings* 1841: 020003. doi:10.1063/1.4982767

#### Peer Reviewed

1

#### Copyright

American Institute of Physics

## Comments

This article was originally published in

AIP Conference Proceedings, volume 1841, issue 1, in 2017. DOI: 10.1063/1.4982767