Deep-cryogenic control voltage generator for quantum dot spin qubits

More than two weeks ago

Design a ultra-low power cryogenic CMOS controller for imec’s spin qubits.

Quantum computation is currently gaining a lot of attention in the active research field. By using the quantum principles of superposition and entanglement an exponential speed-up of certain computation task can be obtained. At the core of each quantum computer lies the qubit; the quantum equivalent of the classical bit. Different physical forms for implementing qubits are studied by research groups around the world. At , the quantum dot spin qubits are, amongst other physical forms, investigated. In quantum dot based qubits, charge is electrically confined in a nanometer scale area. The spin of the electron(s) trapped in the dot is used for "storing" the quantum state of the qubit. To avoid the disturbance of the state by of thermal effects, the qubit needs to be kept at deep-cryogenic temperatures in the range. To reach these low temperatures, special dilution refrigerators are used.  The available cooling power of these refrigerators is limited to around​ 100 µW. Therefore barely no active power consumption can be tolerated inside the refrigerator.

The confinement of the charge in the quantum dot is achieved by using control gates. Each qubit typically has multiple gates biased at specific voltage levels. These voltages are currently generated by lab instruments and are routed through cables to the qubit chip resting at the inside of dilution refrigerator.  For a full quantum computer, which is expected to need thousands to millions of qubits, there would be just too much cabling when this approach is maintained. For this reason, there is research interest to bring all bias voltage circuitry to the inside of refrigerator onto a CMOS chip resting next to the qubit chip.

The goal of this thesis/internship is to design a low power bias voltage generator operating at temperatures for simultaneously controlling multiple of spin quantum dot qubits. 

Type of project: Combination of internship and thesis

Duration: 9 months

Required degree: Master of Engineering Science

Required background: Electrotechnics/Electrical Engineering

Supervising scientist(s): For further information or for application, please contact: Steven Van Winckel (

Only for self-supporting students.

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