Seminar series
Date
Tue, 06 Feb 2024
12:30
12:30
Location
L4
Speaker
Balint Koczor
Organisation
Oxford
Quantum computers are becoming a reality and current generations of machines are already well beyond the 50-qubit frontier. However, hardware imperfections still overwhelm these devices and it is generally believed the fault-tolerant, error-corrected systems will not be within reach in the near term: a single logical qubit needs to be encoded into potentially thousands of physical qubits which is prohibitive.
Due to limited resources, in the near term, we need to resort to quantum error mitigation techniques. I will explain the basic concepts and then discuss my results on exponentially effective error mitigation [PRX 11, 031057 (2021), PRX Quantum, accepted (2024)], including an architecture of multiple quantum processors that perform the same quantum computation in parallel [PR Applied 18, 044064 (2022)]; using their outputs to verify each other results in an exponential suppression of errors.
I will then explain that hybrid quantum-classical protocols are the most promising candidates for achieving early quantum advantage. These have the potential to solve real-world problems---including optimisation or ground-state search---but they suffer from a large number of circuit repetitions required to extract information from the quantum state. I will explain some of our recent results as hybrid quantum algorithms that exploit so-called classical shadows (random unitary protocols) in order to extract and post-process a large amount of information from the quantum computer [PRX 12, 041022 (2022)] and [arXiv:2212.11036]. I will finally identify the most likely areas where quantum computers may deliver a true advantage in the near term.