Colloquium: Dr. Justyna Zwolak | NIST
In-Person PHYS 401
Location
Physics : 401
Date & Time
April 22, 2026, 11:00 am – 12:00 pm
Description
TITLE: Intelligent Tuning of Quantum Dot Devices
ABSTRACT: Semiconductor quantum dot devices are a promising platform for scalable quantum computing. However, scaling from a few qubit arrays to large quantum processing units depends on efficient, reliable ways to set the many gate voltages that place each dot in a qubit-ready regime. Electron confinement and tunneling in quantum dot devices are extremely sensitive to gate voltages and the local electrostatic environment. That sensitivity shows up as changes in charge configuration and decoherence: small voltage drifts can shift tunnel rates, alter readout conditions, and ultimately degrade qubit performance. The challenge is compounded by the fact that the same gates that define a dot also influence nearby electron reservoirs and sensitive charge sensors. As a result, operating quantum-dot qubits is not a one-time setup step—it is a multi-stage calibration process that must be revisited as conditions evolve.
ABSTRACT: Semiconductor quantum dot devices are a promising platform for scalable quantum computing. However, scaling from a few qubit arrays to large quantum processing units depends on efficient, reliable ways to set the many gate voltages that place each dot in a qubit-ready regime. Electron confinement and tunneling in quantum dot devices are extremely sensitive to gate voltages and the local electrostatic environment. That sensitivity shows up as changes in charge configuration and decoherence: small voltage drifts can shift tunnel rates, alter readout conditions, and ultimately degrade qubit performance. The challenge is compounded by the fact that the same gates that define a dot also influence nearby electron reservoirs and sensitive charge sensors. As a result, operating quantum-dot qubits is not a one-time setup step—it is a multi-stage calibration process that must be revisited as conditions evolve.
In this talk, I will present our framework for a modular, autonomous tuning system that bootstraps a quantum-dot device from an uncalibrated state to a qubit-ready operating point. The approach breaks tuning into specialized tasks—such as locating charge transitions, calibrating charge sensors, and setting tunnel couplings—and uses dedicated algorithms for each stage to improve reliability and make the workflow easier to transfer across devices. I will present our group's contributions to this framework, closing with a vision for community-driven, platform-agnostic tuning software that can accelerate calibration at scale, reduce hands-on effort, and help make large quantum-dot arrays practical experimental systems.
