



01667nas a2200157   4500008004100000245007000041210006800111260001400179520117400193653002701367653003101394100001601425700001801441700001301459856003701472       2022                        eng d00aComputational self-testing of multi-qubit states and measurements0 aComputational selftesting of multiqubit states and measurements  c1/31/20223 a<p>Self-testing is a fundamental technique within quantum information theory that allows a classical verifier to force (untrusted) quantum devices to prepare certain states and perform certain measurements on them. The standard approach assumes at least two spatially separated devices. Recently, Metger and Vidick [Quantum, 2021] showed that a single EPR pair of a single quantum device can be self-tested under standard computational assumptions. In this work, we generalize their techniques to give the first protocol that self-tests N EPR pairs and measurements in the single-device setting under the same computational assumptions. We show that our protocol can be passed with probability negligibly close to 1 by an honest quantum device using poly(N) resources. Moreover, we show that any quantum device that fails our protocol with probability at most ϵ must be poly(N,ϵ)-close to being honest in the appropriate sense. In particular, a simplified version of our protocol is the first that can efficiently certify an arbitrary number of qubits of a cloud quantum computer, on which we cannot enforce spatial separation, using only classical communication.</p>10aFOS: Physical sciences10aQuantum Physics (quant-ph)1 aFu, Honghao1 aWang, Daochen1 aZhao, Qi  uhttps://arxiv.org/abs/2201.13430