Southwest Quantum Information and Technology

Schroedinger's cat meets Maxwell's demon: Quantum error correction (that works)

Presenting Author: Steven Girvin, Yale University

Successful quantum error correction requires construction of a quantum "Maxwell's demon" which can remove the entropy generated by errors in the N physical qubits comprising a logical qubit, without learning (and therefore destroying) the quantum information stored in the logical qubit. Because N physical qubits have an error rate N times larger than a single physical qubit, the Maxwell demon must be sufficiently fast and accurate to overcome this factor of N just to reach the 'break-even' point where the lifetime of the quantum information begins to be enhanced. Experiments at Yale have successfully demonstrated quantum error correction that reaches the break-even point for the first time. In addition, recent experiments have demonstrated entanglement between logically encoded qubits. Paradoxically, these successes were achieved by storing the quantum information in objects that are normally considered quite fragile, namely 'Schoedinger cat' states of photons. Elementary: [1] Wiring up quantum systems, R.J. Schoelkopf and S.M. Girvin, Nature 451, 664 (2008). [2] Superconducting Circuits for Quantum Information: An Outlook, M.H. Devoret and R.J. Schoelkopf, Science 339, 1169 (2013). Advanced: [3] Deterministically encoding quantum information in 100-photon Schoedinger cat states, Vlastakis, B., et al. Science 342, 607 (2013). [4] A Schroedinger Cat Living in Two Boxes, Chen Wang, et al., Science 352, 1087 (2016). [5] Extending the lifetime of a quantum bit with error correction in superconducting circuits, Nissim Ofek, et al., Nature 536, 441445 (2016). [6] A CNOT gate between multiphoton qubits encoded in two cavities, Serge Rosenblum, et al., arXiv:1709.05425.

(Session 6 : Friday from 8:30am-9:15am)