Freie Universität Berlin
Once a quantum computation or simulation setup gains in size and coherence new research challenges appear when trying to get a handle on what the experimental device is doing. One of the most immediate questions that emerges is simply: How can I know that the system performs correctly if quantum state tomography is out of reach? Broadly speaking, we would like to devise ways for certifying successful implementations of quantum protocols despite large numbers of degrees of freedom involved in the process. In the talk I will describe the notion of fidelity witnesses which offer an experimentally-friendly way for circumventing the difficulty of measuring the fidelity between a known target quantum state and an unknown experimental preparation. Part of the talk will be devoted to specific fidelity witnesses useful for certifying high-fidelity state preparations of fermionic Gaussian states which recently found an application on the Sycamore quantum processor. Besides giving an overview of what is the current understanding of the range of applicability of the fidelity witness approach to verifying quantum simulators, I will also hint at comparisons to other post-tomographic certification methods.
Zoom meeting details
Topic: Quantum Information and Quantum Computing Working Group
Time: July 1, 2021, 3:15 PM Warsaw
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Meeting ID: 96294497969
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