'Interaction-Free' Channel Discrimination
- URL: http://arxiv.org/abs/2010.00623v1
- Date: Thu, 1 Oct 2020 18:06:56 GMT
- Title: 'Interaction-Free' Channel Discrimination
- Authors: Markus Hasen\"ohrl and Michael M. Wolf
- Abstract summary: We generalize the notion of 'interaction-free' measurement to arbitrary quantum channels.
Our main result is a necessary and sufficient criterion for when it is possible or impossible to discriminate quantum channels in an 'interaction-free' manner.
- Score: 0.0
- License: http://arxiv.org/licenses/nonexclusive-distrib/1.0/
- Abstract: In this work, we investigate the question, which objects one can discriminate
perfectly by 'interaction-free' measurements. To this end, we interpret the
Elitzur-Vaidman bomb-tester experiment as a quantum channel discrimination
problem and generalize the notion of 'interaction-free' measurement to
arbitrary quantum channels. Our main result is a necessary and sufficient
criterion for when it is possible or impossible to discriminate quantum
channels in an 'interaction-free' manner (i.e., such that the discrimination
error probability and the 'interaction' probability can be made arbitrarily
small). For the case where our condition holds, we devise an explicit protocol
with the property that both probabilities approach zero with an increasing
number of channel uses, $N$. More specifically, the 'interaction' probability
in our protocol decays as $\frac{1}{N}$ and we show that this rate is the
optimal achievable one. Furthermore, our protocol only needs at most one
ancillary qubit and might thus be implementable in near-term experiments. For
the case where our condition does not hold, we prove an inequality that
quantifies the trade-off between the error probability and the 'interaction'
probability.
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