PhD, Princeton University, Physics (2019)
MA, Scuola Normale Superiore and University of Pisa, Physics (2014)
BA, Scuola Normale Superiore and University of Pisa, Physics (2012)
- Triunitary quantum circuits PHYSICAL REVIEW RESEARCH 2021; 3 (4)
- Many-Body Physics in the NISQ Era: Quantum Programming a Discrete Time Crystal PRX QUANTUM 2021; 2 (3)
- Entanglement Phase Transitions in Measurement-Only Dynamics PHYSICAL REVIEW X 2021; 11 (1)
Postselection-Free Entanglement Dynamics via Spacetime Duality.
Physical review letters
2021; 126 (6): 060501
The dynamics of entanglement in "hybrid" nonunitary circuits (for example, involving both unitary gates and quantum measurements) has recently become an object of intense study. A major hurdle toward experimentally realizing this physics is the need to apply postselection on random measurement outcomes in order to repeatedly prepare a given output state, resulting in an exponential overhead. We propose a method to sidestep this issue in a wide class of nonunitary circuits by taking advantage of spacetime duality. This method maps the purification dynamics of a mixed state under nonunitary evolution onto a particular correlation function in an associated unitary circuit. This translates to an operational protocol which could be straightforwardly implemented on a digital quantum simulator. We discuss the signatures of different entanglement phases, and demonstrate examples via numerical simulations. With minor modifications, the proposed protocol allows measurement of the purity of arbitrary subsystems, which could shed light on the properties of the quantum error correcting code formed by the mixed phase in this class of hybrid dynamics.
View details for DOI 10.1103/PhysRevLett.126.060501
View details for PubMedID 33635716
Time-Crystalline Eigenstate Order on a Quantum Processor.
Quantum many-body systems display rich phase structure in their low-temperature equilibrium states1. However, much of nature is not in thermal equilibrium. Remarkably, it was recently predicted that out-of-equilibrium systems can exhibit novel dynamical phases2-8 that may otherwise be forbidden by equilibrium thermodynamics, a paradigmatic example being the discrete time crystal (DTC)7,9-15. Concretely, dynamical phases can be defined in periodically driven many-body localized (MBL) systems via the concept of eigenstate order7,16,17. In eigenstate-ordered MBL phases, the entire many-body spectrum exhibits quantum correlations and long-range order, with characteristic signatures in late-time dynamics from all initial states. It is, however, challenging to experimentally distinguish such stable phases from transient phenomena, or from regimes in which the dynamics of few select states can mask typical behavior. Here we implement tunable CPHASE gates on an array of superconducting qubits to experimentally observe an MBL-DTC and demonstrate its characteristic spatiotemporal response for generic initial states7,9,10. Our work employs a time-reversal protocol to quantify the impact of external decoherence, and leverages quantum typicality to circumvent the exponential cost of densely sampling the eigenspectrum. Furthermore, we locate the phase transition out of the DTC with an experimental finite-size analysis. These results establish a scalable approach to studying non-equilibrium phases of matter on quantum processors.
View details for DOI 10.1038/s41586-021-04257-w
View details for PubMedID 34847568
- Floquet Prethermalization in a Bose-Hubbard System PHYSICAL REVIEW X 2020; 10 (2)
- Energetics of Pfaffian-anti-Pfaffian domains PHYSICAL REVIEW B 2020; 101 (4)