High-fidelity operation in spin-qubit registers.
Abstract
We propose to focus on topic B (GASP) and use gate-defined quantum dots to advance new qubit approaches beyond basic demonstrations and demonstrate high-fidelity gate operations in multi-qubit systems. Using strained SiGe heterostructures as host material, we will focus on hole spin qubits in germanium and electron spin-orbit qubits in SiGe wiggle-wells. We will also advance state-of-the-art silicon spin qubits and use these as benchmarks for novel approaches. Our consortium has key expertise in all these platforms, and we have demonstrated high-fidelity single-qubit logic, high-fidelity two-qubit logic, and multi-qubit control up to four and six qubits in germanium and silicon quantum devices. The main thrust of our proposal is to drastically improve, in a reproducible way, the performance within the prospective many-qubit architectures. We will investigate novel silicon germanium heterostructures, explore best qubit encodings, and carefully study qubit control, noise, and cross talk, aiming to increase all fidelities in multi-qubit registers, and to couple such registers to facilitate scaling to larger numbers, without sacrificing important properties. The growth team at Delft will focus on materials development exploiting the existing feedback loops from the measurement teams at Delft, Wisconsin, and Harvard. Material support will also come through HRL via the MIRO program, providing risk mitigation. Quantum dot nanofabrication will advance in a collaborative setting between Delft, Wisconsin, and Harvard, while the Sandia group will accelerate progress through microelectronics process development by advancing device testing, improving the yield, and ensuring fast turnaround. Theory (Delft, UNSW, and Wisconsin) will focus on designing optimal structures, finding optimal operation regimes, and developing strategies to mitigate decoherence and crosstalk. The measurement teams (Delft, Wisconsin, Harvard) will develop protocols to efficiently tune, characterize, and control multi-qubit systems. When comparing architectures, we will focus on fidelities in many-qubit settings, including the effects of unavoidable cross-talk and cross-couplings, to understand how high-fidelity gates can be implemented when scaling up quantum devices. The goal of this program is to demonstrate multi-qubit systems of 5-10 qubits with high-fidelity initialization, control, and readout and show that remote spin qubit registers can be coupled through long-range quantum links. In doing so, we will realize a compelling qubit platform with superior performance and provide a set of principles for the design of high-fidelity gates in future quantum devices with ~100 qubits and above.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 24, 2023
- Source ID
- W911NF2310110
Entities
People
- Menno Veldhorst
Organizations
- Army Contracting Command
- Delft University of Technology
- National Security Agency