07.07.2026Open Position MEP/BEP
Open position MEP: Measurement-induced state transitions induced via junction readout
Quantum computing is being developed to solve problems which are currently impossible for classical computing, which leads to potential widespread application in several fields. The push for fault-tolerant quantum processors is underpinned by the quality of quantum operations, which are susceptible to error. In superconducting quantum processors, the state of the art for control is limited by the duration and infidelity of qubit readout using a coupled resonator.
Circuit diagram of a Transmon coupled to a readout resonator via a Josephson junction. Image taken from [4].
Readout is limited by measurement-induced state transitions (MIST), which limit the strength of the achievable readout signal [1]. New implementations have been shown using a non-linear coupling which leads to less MIST [2], including a recent implementation which utilizes a cross-Kerr readout term from a Josephson junction connecting the readout resonator and qubit, called ‘junction readout’ [3].
In DiCarlo lab, we are working to improve the design of superconducting quantum processors and our control over them. We are looking for a motivated master student (QIST or Applied Physics) to join us to address the readout limitations in current devices. Below is a brief description of the master end project (MEP) offered.
Floquet branch analysis of drive strength with a branch swap. Image taken from [2].
Project Description
You will develop the simulations of the coupled qubit-readout Hamiltonian, in the context of junction readout, to quantify the multi-photon resonances which lead to MIST. You will interpret and apply this simulation to study the readout parameter space and inform the design of future readout devices. Additionally, you will then validate the simulations by participating in the characterization of a device with both junction readout and dispersive readout. If you have a strong background in quantum mechanics and programming and are interested in this challenge, please contact PhD candidate Lucas Hak (l.a.hak[at]tudelft.nl) to learn more about this MEP. For information about our lab and publications: https://qutech.nl/lab/dicarlo-lab-welcome/
References and further reading
[1] Dumas et al., Measurement-Induced transmon ionization, Phys. Rev. X 14, 041023, (2024).
[2] Hazra et al., Readout-induced leakage in superconducting circuits with nonlinear couplings, ArXiv:2606.16055.
[3] Beaulieu et al., Fast, high-fidelity transmon readout with intrinsic Purcell protection via nonperturbative cross-Kerr coupling, ArXiv:2601.04975.
[4] Chapple et al., Balanced cross-Kerr coupling for superconducting qubit readout, Phys. Rev. Lett. 135, 256002 (2025).
