All-optical superconducting qubit readout

Area of Science:

• Quantum Computing
• Cryogenics
• Optoelectronics

Background:

• Superconducting quantum hardware faces scalability challenges due to stringent input-output requirements for error correction in cryogenic environments.
• Existing ultracold electro-optic links for qubit control and readout have been limited by low efficiency, bandwidth, or added noise.
• Classical data centers utilize fiber-optic interconnects to mitigate networking bottlenecks, inspiring similar approaches in quantum systems.

Purpose of the Study:

• To develop an efficient and scalable qubit readout method for superconducting quantum hardware operating at millikelvin temperatures.
• To overcome the limitations of existing electro-optic links, specifically low efficiency, bandwidth, and noise.
• To demonstrate a novel radio-over-fiber approach compatible with superconducting circuits and telecom-wavelength light.

Main Methods:

• Implementation of a radio-over-fiber qubit readout system operating at millikelvin temperatures.
• Utilization of a single device for simultaneous upconversion and downconversion between microwave and optical frequencies.
• Demonstration of all-optical single-shot readout in a circulator-free configuration.

Main Results:

• Successful realization of radio-over-fiber qubit readout at millikelvin temperatures.
• Elimination of the need for active or passive cryogenic microwave equipment through a single-device upconversion/downconversion system.
• Demonstration of circulator-free, all-optical single-shot readout with no observed direct radiation impact on the qubit state.

Conclusions:

• The developed radio-over-fiber qubit readout is compatible with superconducting circuits and telecom-wavelength light, addressing key scalability issues.
• This technology is crucial for establishing modular quantum networks and enabling multiplexed readout for superconducting devices.
• The approach offers a promising solution for efficient and low-noise signal transmission in future quantum computing architectures.