Quantum Enhanced Optimization (QEO)
QEO seeks to harness quantum effects required to enhance quantum annealing solutions to hard combinatorial optimization problems. The physics underlying quantum enhancement will be corroborated by design and demonstration of research-scale annealing test beds comprised of novel superconducting qubits, architectures, and operating procedures. All work will serve to demonstrate a plausible path to enhancement and a basis for design of application-scale quantum annealers.
State preservation by repetitive error detection in a superconducting quantum circuit
In 2015 IRAPA stated: Quantum computing becomes viable when a quantum state can be protected from environment-induced error. If quantum bits (qubits) are sufficiently reliable, errors are sparse and quantum error correction (QEC) is capable of identifying and correcting them. Adding more qubits improves the preservation of states by guaranteeing that increasingly larger clusters of errors will not cause logical failure—a key requirement for large-scale systems. Using QEC to extend the qubit lifetime remains one of the outstanding experimental challenges in quantum computing. Here we report the protection of classical states from environmental bit-flip errors and demonstrate the suppression of these errors with increasing system size. We use a linear array of nine qubits, which is a natural step towards the two-dimensional surface code QEC scheme7, and track errors as they occur by repeatedly performing projective quantum non-demolition parity measurements. Relative to a single physical qubit, we reduce the failure rate in retrieving an input state by a factor of 2.7 when using five of our nine qubits and by a factor of 8.5 when using all nine qubits after eight cycles. Additionally, we tomographically verify preservation of the non-classical Greenberger–Horne–Zeilinger state. The successful suppression of environment-induced errors will motivate further research into the many challenges associated with building a large-scale superconducting quantum computer.
Source: https://www.iarpa.gov/index.php/newsroom/iarpa-in-the-news/2015/457-state-preservation-by-repetitive-error-detection-in-a-superconducting-quantum-circuit?highlight=WyJxdWFudHVtIiwiY29tcHV0ZXIiLCJjb21wdXRlcidzIiwicXVhbnR1bSBjb21wdXRlciJd