Spin-Valley Qubit Dynamics in Exchange-Coupled Silicon Quantum Dots

  title={Spin-Valley Qubit Dynamics in Exchange-Coupled Silicon Quantum Dots},
  author={Donovan Buterakos and Sankar Das Sarma},
  journal={PRX Quantum},
The presence of valley states is a significant obstacle to realizing quantum information technologies in Silicon quantum dots, as leakage into alternate valley states can introduce errors into the computation. We use a perturbative analytical approach to study the dynamics of exchange-coupled quantum dots with valley degrees of freedom. We show that if the valley splitting is large and electrons are not properly initialized to valley eigenstates, then time evolution of the system will lead to… 

Figures from this paper

Looped Pipelines Enabling Effective 3D Qubit Lattices in a Strictly 2D Device

Many quantum computing platforms are based on a fundamentally two-dimensional physical layout. However, there are advantages (for example in fault-tolerant systems) to having a 3D architecture. Here

Microwave-Frequency Scanning Gate Microscopy of a Si/SiGe Double Quantum Dot.

Conventional transport methods provide quantitative information on spin, orbital, and valley states in quantum dots but lack spatial resolution. Scanning tunneling microscopy, on the other hand,



Universal quantum computing with spin and valley states

We investigate a two-electron double quantum dot with both spin and valley degrees of freedom as they occur in graphene, carbon nanotubes or silicon and regard the 16-dimensional space with one

Spin-valley lifetimes in a silicon quantum dot with tunable valley splitting.

It is demonstrated that valley separation can be accurately tuned via electrostatic gate control in a metal-oxide-semiconductor quantum dot, providing splittings spanning 0.3-0.8 meV, with a ratio in agreement with atomistic tight-binding predictions.

Coherent transfer of quantum information in a silicon double quantum dot using resonant SWAP gates

Spin-based quantum processors in silicon quantum dots offer high-fidelity single and two-qubit operation. Recently multi-qubit devices have been realized; however, many-qubit demonstrations remain

Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot.

A long-lived single-electron spin qubit in a Si/SiGe quantum dot with all-electrical two-axis control is demonstrated and advances strongly improve the prospects for quantum information processing based on quantum dots.

Universal quantum logic in hot silicon qubits

The demonstration of ‘hot’ and universal quantum logic in a semiconductor platform paves the way for quantum integrated circuits that host both the quantum hardware and its control circuitry on the same chip, providing a scalable approach towards practical quantum information processing.

A two-qubit logic gate in silicon

A two-qubit logic gate is presented, which uses single spins in isotopically enriched silicon and is realized by performing single- and two- qubits operations in a quantum dot system using the exchange interaction, as envisaged in the Loss–DiVincenzo proposal.

Integrated silicon qubit platform with single-spin addressability, exchange control and single-shot singlet-triplet readout

An integrated device platform incorporating a silicon metal-oxide-semiconductor double quantum dot that is capable of single-spin addressing and control via electron spin resonance, combined with high-fidelity spin readout in the singlet-triplet basis is demonstrated.

Universal quantum computation with the exchange interaction

An explicit scheme is introduced in which the Heisenberg interaction alone suffices to implement exactly any quantum computer circuit, at a price of a Factor of three in additional qubits, and about a factor of ten in additional two-qubit operations.

A programmable two-qubit quantum processor in silicon

The entanglement in the processor is characterized by using quantum-state tomography of Bell states, measuring state fidelities of 85–89 per cent and concurrences of 73–82 per cent, paving the way for larger-scale quantum computers that use spins confined to quantum dots.

Shuttling a single charge across a one-dimensional array of silicon quantum dots

Significant advances have been made towards fault-tolerant operation of silicon spin qubits, with single qubit fidelities exceeding 99.9%, several demonstrations of two-qubit gates based on exchange