Quantum Overlapping Tomography

Jordan Cotler, Frank Wilczek

Research output: Contribution to journalArticlepeer-review

61 Scopus citations


It is now experimentally possible to entangle thousands of qubits, and efficiently measure each qubit in parallel in a distinct basis. To fully characterize an unknown entangled state of n qubits, one requires an exponential number of measurements in n, which is experimentally unfeasible even for modest system sizes. By leveraging (i) that single-qubit measurements can be made in parallel, and (ii) the theory of perfect hash families, we show that all k-qubit reduced density matrices of an n qubit state can be determined with at most eO(k)log2(n) rounds of parallel measurements. We provide concrete measurement protocols which realize this bound. As an example, we argue that with near-term experiments, every two-point correlator in a system of 1024 qubits could be measured and completely characterized in a few days. This corresponds to determining nearly 4.5 million correlators.

Original languageEnglish (US)
Article number100401
JournalPhysical Review Letters
Issue number10
StatePublished - Mar 13 2020

ASJC Scopus subject areas

  • General Physics and Astronomy


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