Fast and Modular Spin Qubit Arrays (FMSpins)
Abstract
Semiconductor spin qubits have satisfied the DiVincenzo criteria for scalable quantum computing. Several research groups have recently demonstrated high-fidelity spin state initialization, readout, single-qubit and two-qubit control. This research program is focused on demonstrating fast control and readout of spin qubit arrays, as well as developing a modular spin qubit architecture, wherein two spatially separated two-qubit modules are coherently coupled through a quantum interconnect. Several promising approaches exist for long-range coupling of spin qubits, including exchange coupling through large intermediary quantum dots, circuit quantum electrodynamics (cQED), and the physical transfer of spin-based quantum information through charge shuttling. We will demonstrate coherent coupling of two or more two-qubit modules using spin shuttling. In parallel, the theory team will estimate the fidelity of various spin transfer protocols that are based on cQED. The theory team will also develop quantum characterization verification and validation (QCVV) protocols that can be applied to characterize the overall fidelity of our modular spin qubit architecture. In the area of quantum control and readout, the research team has two major objectives. The first is to build upon recent gains in single- and two-qubit control fidelities through fundamental investigations of the fidelity-limiting mechanisms. Current bottlenecks are limitations in the maximum Rabi frequency that can be achieved with electric dipole spin resonance, crosstalk during single qubit control due to microwave cross-coupling and residual exchange, limited dynamic range of the exchange coupling, and slow gate calibration times. A second objective is to develop cutting-edge quantum control and readout protocols that have the potential to greatly reduce the required qubit drive times and powers, significantly reduce the readout time, and enable multiplexed readout of spin qubit arrays. The team will focus on implementations involving Loss-DiVincenzo (LD) spin qubits, where quantum information is encoded in the spin of a single electron. LD qubits are generally controlled using electric dipole spin resonance (EDSR) in a magnetic field gradient and coherently coupled using the exchange interaction. While impressive progress has been made in controlling LD qubits with high fidelity, most demonstrations involve just single or two-qubit devices. Our team has been at the forefront of efforts to develop scalable semiconductor quantum devices, including pioneering demonstrations of resonant two-qubit gates, as well as spin coupling and readout using cQED.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Apr 19, 2023
- Source ID
- W911NF2310104
Entities
People
- Jason R Petta
Organizations
- Army Contracting Command
- National Security Agency
- University of California, Los Angeles