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On the Path to Cryogenic Control of Quantum Processors

Thursday, February 21, 2019

Posted by Joseph Bardin, Visiting Faculty Researcher and Erik Lucero, Staff Research Scientist and Hardware Lead, Google AI Quantum Teampractical problemsGoogle AI Quantum teamCurrent thresholds suggest Bristleconekelvinwe presentedInternational Solid State Circuits Conference

Google’s first generation cryogenic-CMOS single-qubit controller (center and zoomed on the right) packaged and ready to be deployed inside our cryostat. The controller measures 1mm by 1.6mm.

How to Control 72 Qubitsour lab in Santa Barbara

Research Scientist Amit Vainsencher checking the wiring on Bristlecone in one of Google's flagship cryostats. Blue coaxial cables are connected from custom analog control electronics (server rack on the right) to the quantum processor.

A Cool IdeaUniversity of Massachusetts Professor Joseph Bardinwithin

Schematic of the cryogenic-CMOS qubit controller mounted on the 3 kelvin stage of our dilution refrigerator and connected to a qubit. Our standard qubit control electronics were connected in parallel to enable control and measurement of the qubit as an in-situ check experiment.

Performance at Low TemperatureT1Rabi oscillationssingle qubit gates

Comparison of the qubit coherence time measured using the standard and cryogenic quantum controllers.

Measured Rabi amplitude oscillations using the cryogenic controller. The green and black traces are the probability of measuring the qubits in the 1 and 0 states, respectively.

Next StepsAcknowledgementsThis work was carried out with the support of the Google Visiting Researcher Program while Prof. Bardin, an Associate Professor with the University of Massachusetts Amherst, was on sabbatical with the Google AI Quantum Team. This work would not have been possible without the many contributions of members of the Google AI Quantum team, especially Evan Jeffrey for his integration of the cryo-CMOS controller into the qubit calibration software, Ted White for his on-demand qubit calibrations and Trent Huang for his tireless design rules checks.