Program
Full Program | Thursday | Friday | Saturday | All Sessions | Posters | Talks
LSU SQuInT Event Map
SESSION 2: Quantum control (Theatre)Chair: (Bryan Eastin (Northrop Grumman)) | |
| 10:30am - 11:15am | Christiane Koch, Kassel Quantum optimal control of superconducting circuits | Abstract. Quantum optimal control has grown into a versatile tool for quantum technology. Its key application is to identify performance bounds, for tasks such as state preparation or quantum gate implementation, within a given architecture. One such bound is the quantum speed limit, which determines the shortest possible duration to carry out the task at hand. Typical examples include the creation of entanglement or quantum error correction. To date, these tasks have been optimized for known, fixed parameters of the system. I will show that a fully numerical quantum optimal control approach can go even further and, using the most advanced control techniques, map out the entire parameter landscape for two superconducting transmon qubits. This allows to determine the global quantum speed limit for a universal set of gates with gate errors limited solely by the qubit lifetimes. While the interaction of qubits with their environment is typically regarded as detrimental, this does not need to be the case. I will show that the back-flow of amplitude and phase encountered in non-Markovian dynamics can be exploited to carry out quantum control tasks for a superconducting circuit that could not be realized if the system was isolated. The control is facilitated by a few strongly coupled, sufficiently isolated environmental modes. These can be found in a variety of solid-state devices other than superconducting circuits, for example in color centers in nanodiamonds or nanomechanical oscillators. |
| 11:15am - 11:45am | Xiaoting Wang, Louisiana State Experimental time-optimal universal control of spin qubits in solids | Abstract. Quantum control of systems plays an important role in modern science and technology. The ultimate goal of quantum control is to achieve high-fidelity universal control in a time-optimal way. Although high-fidelity universal control has been reported in various quantum systems, experimental implementation of time-optimal universal control remains elusive. Here, we report the experimental realization of time-optimal universal control of spin qubits in diamond. By generalizing a recent method for solving quantum brachistochrone equations [X. Wang et al., Phys. Rev. Lett. 114, 170501 (2015)], we obtained accurate minimum-time protocols for multiple qubits with fixed qubit interactions and a constrained control field. Single- and two-qubit time-optimal gates are experimentally implemented with fidelities of 99% obtained via quantum process tomography. Our work provides a time-optimal route to achieve accurate quantum control and unlocks new capabilities for the emerging field of time-optimal control in general quantum systems. |
| 11:45am - 12:15pm | Jeffrey Epstein, UC Berkeley Speed limits for quantum control of local spin systems | Abstract. We show that the fundamental limits on quantum many-body dynamics from the Lieb-Robinson bound yield speed limits on two quantum control tasks, state transfer and entanglement sharing. We derive analytic speed limits on these tasks in nearest-neighbor coupled spin chains and lattices, providing optimal speeds for comparison with numerical optimal control results in the many-body setting. |
SQuInT Chief Organizer
Akimasa Miyake, Assistant Professor
amiyake@unm.edu
SQuInT Co-Organizer
Mark M. Wilde, Assistant Professor LSU
mwilde@phys.lsu.edu
SQuInT Administrator
Gloria Cordova
gjcordo1@unm.edu
505 277-1850
SQuInT Event Coordinator
Karen Jones, LSU
kjones@cct.lsu.edu
SQuInT Founder
Ivan Deutsch, Regents' Professor
ideutsch@unm.edu
