Open Position Master, PhD and Post-doc

Vortex-based Digital Superconducting Diode

Recent improvements in cryogenic and nanofabrication allow us not only show concepts of superconducting electronics but open a path to a real competition against semiconducting one. One of a basic element of any circuits is the diode. One of possible realizations of the superconducting diode is based on the operation of Abrikosov vortices. The main advantages of this type is a relative fabrication simplicity. But optimization are still required in terms of design and operating protocols. Coupling vortices with external periodic drive can lead to effect of their synchronous motion . Using that effect, it is possible to make a digital version of the superconducting diode : vortices move synchronously “1” or asynchronously “0”. In this internship we propose to study properties of a vortex-based superconducting diode and optimizing its parameters for the best efficiency.

Building Integrated SNSPDs to Develop an hBN Quantum Photonic Platform Including Single-Photon Emitters.

The rise of quantum technologies has highlighted two major challenges : the precise control of coherent quantum processes and the efficient large-scale conversion of quantum results into classical signals. The quantum photonics approach relies on single-photon sources and detectors, which are essential com- ponents for many applications in quantum information science. This proposal focuses on the experimental realization of integrated superconducting nanowire single-photon detectors in hexagonal boron nitride (hBN) photonic circuits. The project aims to achieve a fully integrated hBN quantum photonic platform where single photons are generated, routed, and detected on the same chip with high efficiency.

Dynamical Coulomb blockade with NbN metamaterial resonators

The ability to confine light at very small volumes is of paramount importance in order to enhance light-matter interaction both for devices and fundamental studies. The Terahertz and sub-THz spectral domains are particularly prominent for building metallic resonators with ultra-sub-wavelength mode volumes. Indeed, the corresponding wavelengths are large (wavelength= 1mm – 100µm), one can leverage from nanofabrication techniques with nanometer resolution, and metals feature low losses, and even superconducting materials such as NbN are available. In the present project, we will exploit such resonators made of NbN in order to realize and study an elementary system for both electronic transport and light-matter interaction : a semiconductor tunnel junction coupled with an ultra-subwavelength metamaterial resonator. This structure can operate in the Dynamical Coulomb Blockade, where the tunneling of electrons is coupled to the electromagnetic fluctuations of the resonator, providing thus a probe for the its quantum state. Amongs other applications, such device can be used to perform quantum measurements of NBN qubits operating in the 100 GHz range.

Quantum devices in the ultra-strong light-matter coupling regime

The aim of the internship is to explore microcavity-coupled optoelectronic quantum devices which operate in the ultra-strong light-matter coupling regime. These devices are based on quantum well heterostructures integrated with multimode photonic microcavities and metamaterials. Such architectures can dramatically enhance light–matter interactions, enabling access to the ultra-strong coupling regime, which defines new frontiers in cavity quantum electrodynamics. In this regime, electronic excitations in quantum wells hybridize with optical modes of microcavities to form new coupled states—cavity polaritons—that can exhibit strikingly non-classical properties. Such properties can be uncovered by electrical transport measurements or through the non-linear optical conversion which takes place under strong coherent pump. As an intern, the candidate will characterize optoelectronic devices that have been already fabricated in clean room. She/he will thus acquire advanced training in infrared spectroscopy and electrical measurements of quantum devices, including in cryogenic conditions. The internship can be followed by a PhD project specifically focused on non-linear optical effects in such devices. The PhD funding is available through an ANR project.