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Spin Quantum Computing in Silicon
Spin Quantum Computing in Silicon
The spin states of a single electron represent the quintessential quantum two-level system, which can be utilized as a promising qubit candidate, when hosted in a suitable solid-state system. Due to a weak spin-orbit coupling, and absence of nuclear spins, electron spin qubits in isotopically-purified silicon exhibit excellent coherence properties. With ready access to the mature techniques and resources of the semiconductor microelectronics industry, the quantum computing technology based on spin qubits hosted in silicon quantum dots is therefore gaining significant attention worldwide.
Q-Si Lab is currently spearheading one of the two research efforts on spin quantum computing in India. Funded by the DST and the DRDO, our work aims to establish the basic functionalities of the spin quantum computing scheme, and scale up the architecture to 20 qubits, within the next 5 years. Starting from the epitaxially-grown high-quality Si/SiGe quantum well heterostructures, we fabricate the electrostatically defined quantum dots which host the spin qubits, and control, manipulate and measure them at mK temperatures.
SEM image of a Si/SiGe quantum dot device.
Quantum dots in GaAs/AlGaAs heterostructures
Quantum dots in GaAs/AlGaAs heterostructures
While silicon dominates as the host semiconductor for realization of spin qubits, quantum dots in GaAs/AlGaAs heterostructures provided the initial platform for the development of the spin quantum computing (Spin-QC) scheme. Despite certain fundamental limitations, GaAs/AlGaAs-based spin qubits still continue to serve as the test-bed for optimizing existing, and probing new, capabilities of the spin-QC architecture.
In Q-Si Lab, we fabricate spin qubit arrays in the GaAs/AlGaAs heterosystems, particularly to study the measurement challenges related to scalability of spin-QC. We are also interested in transport studies of quantum dot systems, with focus on different aspects of quantum technologies, such as entanglement generation and swapping, quantum heat engines etc.
SEM image of GaAs / AlGaAs quantum dot device.
Coulomb blockade spectroscopy of a SET charge sensor
Coulomb blockade spectroscopy of a SET charge sensor
Coulomb blockade spectroscopy of a quantum dot in the array
Coulomb blockade spectroscopy of a quantum dot in the array
Honeycomb diagram corresponding to a coupled double-quantum dot from the array.
Honeycomb diagram corresponding to a coupled double-quantum dot from the array.
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