



@article {3307,
	title = {Effect of non-unital noise on random circuit sampling},
	year = {2023},
	month = {6/28/2023},
	abstract = {<p>In this work, drawing inspiration from the type of noise present in real hardware, we study the output distribution of random quantum circuits under practical non-unital noise sources with constant noise rates. We show that even in the presence of unital sources like the depolarizing channel, the distribution, under the combined noise channel, never resembles a maximally entropic distribution at any depth. To show this, we prove that the output distribution of such circuits never anticoncentrates \&mdash; meaning it is never too \&quot;flat\&quot; \&mdash; regardless of the depth of the circuit. This is in stark contrast to the behavior of noiseless random quantum circuits or those with only unital noise, both of which anticoncentrate at sufficiently large depths. As consequences, our results have interesting algorithmic implications on both the hardness and easiness of noisy random circuit sampling, since anticoncentration is a critical property exploited by both state-of-the-art classical hardness and easiness results.</p>},
	url = {https://arxiv.org/abs/2306.16659},
	author = {Bill Fefferman and Soumik Ghosh and Michael Gullans and Kohdai Kuroiwa and Kunal Sharma}
}
@article {2872,
	title = {Estimating distinguishability measures on quantum computers},
	year = {2021},
	month = {8/18/2021},
	abstract = {<p>The performance of a quantum information processing protocol is ultimately judged by distinguishability measures that quantify how distinguishable the actual result of the protocol is from the ideal case. The most prominent distinguishability measures are those based on the fidelity and trace distance, due to their physical interpretations. In this paper, we propose and review several algorithms for estimating distinguishability measures based on trace distance and fidelity, and we evaluate their performance using simulators of quantum computers. The algorithms can be used for distinguishing quantum states, channels, and strategies (the last also known in the literature as \&quot;quantum combs\&quot;). The fidelity-based algorithms offer novel physical interpretations of these distinguishability measures in terms of the maximum probability with which a single prover (or competing provers) can convince a verifier to accept the outcome of an associated computation. We simulate these algorithms by using a variational approach with parameterized quantum circuits and find that they converge well for the examples that we consider.\&nbsp;</p>},
	url = {https://arxiv.org/abs/2108.08406},
	author = {Rochisha Agarwal and Soorya Rethinasamy and Kunal Sharma and Mark M. Wilde}
}
