Multi-qubit operations using silicon-MOS quantum dots
Abstract
This Proposal sets out a detailed and achievable work plan for the demonstration of high-fidelity multi-qubit logic based on spins confined in silicon metal-oxide-semiconductor (SiMOS) quantum dots that are compatible with today s Si CMOS manufacturing, offering the long-term prospect of large-scale quantum processors integrating millions of qubits. The research project builds on technologies developed in pioneering work on silicon qubits by Profs. Dzurak and Morello al UNSW, first using single-P atoms, but more recently using lithographically-defined SiMOS quantum dots. These include: (i) the firsf single-shot electron spin readout in Si, using a SiMOS reservoir/sensor [Nature 467, 687 (2010)]; (ii) the first electron spin qubit in Si, based on a P-atom [Nature 489, 541 (2012)]; (iii) demonstration of a high-fidelity (FC = 99.6%) SiMOS quantum dot qubit in 28Si [Nature Nano. 9, 981 (2014)]; and (vii) the first two-qubit logic gate in silicon using exchange-coupled SiMOS quantum dots [Nature 526, 410 (2015)]. The experimental program is based on a well-established SiMOS quantum dot (Q-dot) qubit platform developed by Dzurak, and systematically builds towards entangling operations on 4-, 5- & 6-qubit devices by Year-4. Dzurak s team have recently shown that SiMOS Q-dots can be conveniently exchange coupled in a way that makes them ideal for straight forward extensibility based on a linear array of Q-dots. In this scheme [Nature 526, 410 (2015)] 1-qubit control is enabled via electron spin resonance (ESR) pulses while 2-qubit gates are realized using direct electron-electron exchange between neighboring dots. This linear array approach to near-term extensibility provides an ideal proving ground for the functionality of SiMOS spin qubits, since it allows a variety of multi-qubit operations to be performed, including studies of qubit error detection. 28Si epilayer wafers for device fabrication throughout the program are available via our existing collaboration with Prof. Itoh (Keio U.) - Letter of Support available upon request. To tackle the challenges facing SiMOS multi-qubit operations we have assembled a multi-disciplinary team of PIs comprising leading experimentalists and theorists in the field of semiconductor qubits, with each PI focusing on a key problem/issue. We identify the following key challenges, and the methods that we will undertake to address them: (i) Charge and environmental noise related to the Si/SiO2 materials system and external sources. A team at HRL Laboratories (Gyure, Ladd) will work with UNSW PIs to extract microscopic noise mechanisms from experimental data and develop strategies to mitigate them. (ii) Predictable qubit operational parameters, such as electron g-factor, exchange couplings, etc. become even more important as the number of qubits increases. These will be modeled by PI Gyure (HRL) by adapting full-CI codes, and by PIs Rahman and Klimeck (Purdue) with NEMO atomistic tight-binding. (iii) Qubit characterization , verification and validation (QCVV) protocols will be developed by PIs Bartlett and Flammia (U Sydney), tailored to our SiMOS Q-dot qubits, including algorithm-based benchmarking of multi-qubit systems . (v) Non-demolition single -shot dispersive spin readout will significantly reduce device complexity, and allow parity measurements for error detection. PI Reilly (U Sydney) will develop gate-based dispersive readout specifically for our SiMOS Q-dot qubits. (vi) Experimental protocols for multi -qubit operations in silicon will only be possible after detailed device and materials design to mitigate noise, and device parameter variability, and will require sophisticated timing and pulse shaping techniques. These experiments, led by PI Dzurak (UNSW), will necessarily depend on input from all of the above sub-projects, both theoretical and engineering-based.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 11, 2018
- Source ID
- W911NF1710198
Entities
People
- Andrew S. Dzurak
Organizations
- Army Contracting Command
- National Security Agency
- University of New South Wales