Mixing Signals at Millikelvin: A Cryogenic Adder circuit for Spin Qubits

Semiconductor quantum dot spin qubits require broadband arbitrary waveforms to dynamically control qubit coupling and charge occupation during qubit initialization, readout, and interaction. When operated at deep cryogenic temperatures below 1 K, these waveforms must span frequencies from near DC to several hundred megahertz, while maintaining low noise and high resolution.

A major challenge is the delivery of these analogue signals across such a wide bandwidth from room-temperature electronics to a chip inside a cryostat, without introducing distortion or additional noise.

This internship aims to:

• Develop and design an analogue adder circuit that combines the output of a high-resolution DC voltage source with that of a fast arbitrary waveform generator (AWG). The circuit must provide DC coupling of the AWG signal, high bandwidth, and low power consumption. Development will take place in close collaboration with the cryogenic electronics expertise center at imec.
• Design, implement, and experimentally evaluate a practical prototype of the adder circuit in close collaboration with the quantum computing expertise center at imec. This will include integrating the circuit into a relevant test setup, performing electrical and functional measurements, and assessing performance metrics such as bandwidth, linearity, noise, and stability under operating conditions relevant for quantum computing applications.
• Document, analyze, and report the experimental results in a clear and structured manner for the involved expertise centers. This will include comparing measured performance against design targets and simulations, discussing limitations and trade-offs, and providing recommendations for potential improvements or future iterations of the circuit.

Type of internship: Master internship

Duration: 3-6 Months

Required educational background: Electrotechnics/Electrical Engineering

University promotor: Kristiaan De Greve (KU Leuven)

Supervising scientist(s): For further information or for application, please contact Bart Raes ([email protected]) and Alican Caglar ([email protected])

The reference code for this position is 2026-INT-011. Mention this reference code in your application.

Imec allowance will be provided for students studying at a non-Belgian university.

Applications should include the following information:

• resume
• motivation
• current study

Incomplete applications will not be considered.