PhD Position Cryo-CMOS Readout Circuit for Single-Photon Detectors for Quantum Computers

Shape the Future of Quantum Technology with TU Delft

Are you ready to shape the future of quantum technology? Join our vibrant team in designing and demonstrating cryo-CMOS integrated circuits to interface quantum computers and quantum sensors!

Job Description

Quantum computers promise to solve problems intractable by classical digital computers, while quantum sensors can offer unprecedented accuracy and sensitivity in detecting very small quantities. However, quantum devices typically operate at cryogenic temperatures, thus requiring long, bulky, and unreliable wires to connect to their room-temperature control electronics. This wiring bottleneck hinders the system's scalability and performance. As a PhD student in Electrical Engineering at TU Delft, you will overcome this bottleneck by building the cryogenic interface for future quantum systems.

In our group, we have pioneered the use of CMOS integrated circuits operating at cryogenic temperatures (cryo-CMOS). We adopt standard CMOS technologies to leverage their large-scale integration, as required for future large-scale quantum computers and cryogenic sensors, and to enhance their performance. CMOS devices are functional at temperatures as low as 4 K and below, but their behavior differs significantly from that at room temperature, including an increased threshold voltage, a higher driving current, and lower thermal noise. The challenges lie in exploiting the advantages of cryogenic operation, such as the lower thermal noise, while circumventing device non-idealities by inventing innovative circuit architectures and systems that can outperform the state-of-the-art. Although we have demonstrated several high-performance cryo-CMOS circuits and systems over the last decade, your challenge will be to demonstrate new functionalities and push the boundaries of circuit performance and knowledge.

In this project, you will develop the cryogenic interface for extremely sensitive cryogenic single-photon detectors, the Superconducting Nanowire Single Photon Detectors (SNSPDs) developed by our partner Single Quantum. Thanks to their superior performance, those sensors are currently used for the readout of quantum bits (qubits) in the photonic quantum computers developed by our partner Quix. However, commercially available SNSPD systems are limited to a maximum of 48 channels, while tens of thousands of channels are needed to enable large-scale quantum computation with practical applications. Although it is in principle possible to reliably fabricate a large number of detectors and connect the large number of required optical fibers to the quantum computer, a strict bottleneck in the number of electrical interconnects between the cryogenic photon detectors and their room-temperature read-out hinders the system scalability. To overcome this bottleneck, you will demonstrate a scalable area-efficient ultra-low-power cryogenic electronic interface for single-photon detectors that will enable the readout of 1000+ channels within the cooling constraints of existing cryogenic refrigerators.

You will design the full read-out chain exceeding state-of-the-art performance and able to address 1000+ channels all within a very strict power budget. The read-out will comprise low-noise amplifiers, time taggers to measure the photon arrival time, and an efficient data transfer to the room-temperature controller. Over the course of your PhD, you will devise innovative system architectures and circuits, design several prototypes of cryo-CMOS circuits, tape them out in advanced CMOS technologies, and characterize the resulting prototypes in our advanced cryogenic electrical characterization laboratory.

Your results will advance the state-of-the-art in cryo-CMOS circuit design and will result in presentations at top conferences for advances in integrated circuits and publications in high-impact scientific journals. Your cryo-CMOS readout will be integrated into the readout system for photon-based quantum computers developed by TU Delft and our industrial partners, thus achieving a real impact in the field of quantum technologies.

Job Requirements

• A MSc degree in Electrical Engineering or a related field.
• Strong interest and strong background in analog circuit design; any practical experiences in circuit design, either in academia or industry, is a plus, but not a necessity.
• Good analytical, creativity and problem-solving skills.
• Excellent communication skills in English, both written and oral.
• Ability and eagerness to work in an international collaborative environment.

About TU Delft

Delft University of Technology is built on strong foundations. As creators of the world-famous Dutch waterworks and pioneers in biotech, TU Delft is a top international university combining science, engineering and design. It delivers world class results in education, research and innovation to address challenges in the areas of energy, climate, mobility, health and digital society. For generations, our engineers have proven to be entrepreneurial problem-solvers, both in business and in a social context.

Faculty of Electrical Engineering, Mathematics and Computer Science

The Faculty of Electrical Engineering, Mathematics and Computer Science (EEMCS) brings together three scientific disciplines. Combined, they reinforce each other and are the driving force behind the technology we all use in our daily lives. Technology such as the electricity grid, which our faculty is helping to make completely sustainable and future-proof. At the same time, we are developing the chips and sensors of the future, whilst also setting the foundations for the software technologies to run on this new generation of equipment – which of course includes AI. Meanwhile we are pushing the limits of applied mathematics, for example mapping out disease processes using single cell data, and using mathematics to simulate gigantic ash plumes after a volcanic eruption. In other words: there is plenty of room at the faculty for ground-breaking research. We educate innovative engineers and have excellent labs and facilities that underline our strong international position. In total, more than 1000 employees and 4,000 students work and study in this innovative environment.

Conditions of Employment

• Doctoral candidates will be offered a 4-year period of employment in principle, but in the form of 2 employment contracts. An initial 1.5 year contract with an official go/no go progress assessment within 15 months. Followed by an additional contract for the remaining 2.5 years assuming everything goes well and performance requirements are met.
• Salary and benefits are in accordance with the Collective Labour Agreement for Dutch Universities, increasing from €3059 - €3881 gross per month, from the first year to the fourth year based on a fulltime contract (38 hours), plus 8% holiday allowance and an end-of-year bonus of 8.3%.
• As a PhD candidate you will be enrolled in the TU Delft Graduate School. The TU Delft Graduate School provides an inspiring research environment with an excellent team of supervisors, academic staff and a mentor. The Doctoral Education Programme is aimed at developing your transferable, discipline-related and research skills.
• The TU Delft offers a customisable compensation package, discounts on health insurance, and a monthly work costs contribution. Flexible work schedules can be arranged.

Will you need to relocate to the Netherlands for this job? TU Delft is committed to make your move as smooth as possible! The HR unit, Coming to Delft Service, offers information on their website to help you prepare your relocation. In addition, Coming to Delft Service organises events to help you settle in the Netherlands, and expand your (social) network in Delft. A Dual Career Programme is available, to support your accompanying partner with their job search in the Netherlands.

If you would like more information about this vacancy or the selection procedure, please contact Fabio Sebastiano, via f.sebastiano@tudelft.nl.