Rare-earth based quantum memory

Ecole normale supérieure de Lyon; France; On-site; EUR 20,000 - 23,000; Full time

Job summary

Ecole normale supérieure de Lyon invites applications for a First Stage Researcher (R1) PhD position in quantum physics, focusing on random-access quantum memory using spin ensembles in CaWO4. The project advances coherence, integration with superconducting qubits, and on-chip implementations with collaborations in Paris.

The funded PhD will start Oct 1, 2027 in Lyon, with potential later involvement in Paris, and is supported by an industrial fellowship.

Qualifications

• Master's degree or equivalent required.
• English language proficiency required (level: Excellent).

Responsibilities

• Conduct PhD research on random-access quantum memory in spin ensembles and related quantum systems.
• Collaborate with ChimieTech and PStash in Paris and Lyon.
• Deliver milestones, publish results, and contribute to the project goals.

Skills

Excellent English

Education

Master Degree or equivalent

Job description

Organisation/Company Ecole normale supérieure de Lyon Research Field Physics » Quantum mechanics Physics » Solid state physics Researcher Profile First Stage Researcher (R1) Positions PhD Positions Application Deadline 31 Aug 2027 - 08:30 (Europe/Paris) Country France Type of Contract Temporary Job Status Full-time Hours Per Week 38 Offer Starting Date 1 Oct 2027 Is the job funded through the EU Research Framework Programme? Not funded by a EU programme Is the Job related to staff position within a Research Infrastructure? No

Offer Description

A system able to store several quantum states, with the ability to absorb and retrieve a given state on demand, is dubbed a Random-Access Quantum Memory [1]. Such devices are critical for applications such as quantum repeaters, parallel quantum processing, and high-precision measurements. While various platforms -such as atomic ensembles, superconducting circuits, and mechanical oscillators- have demonstrated quantum memory capabilities, they often face trade-offs between coherence time, capacity, and coupling strength. Ensembles of electron spins for microwave quantum state storage combines three advantages. 1) They can offer storage times longer by two orders of magnitude compared to superconducting qubits [2]. 2) They have a small footprint, and are compatible with superconducting qubits. 3) Protocols exist for storing multiple states into the same device, and can be used to reduce the number of required qubits for quantum algorithm [3]. However, current
spin ensemble memories suffer from low storage efficiency (<10%) due to a fundamental trade-off: high spin concentration enhances coupling to microwave circuits but reduces coherence.

To overcome this, we propose exploring a novel spin system-ytterbium atoms embedded in CaWO₄-which maintains state-of-the-art coherence at much higher concentrations than previously studied systems [4]. Additionally, this system can operate at zero magnetic field, making it highly compatible with superconducting qubits. This compatibility opens
the door to on-chip integration of spin ensembles and superconducting qubits, similar to early proof-of-concept demonstrations [5].
The project will center around two milestones. We will first test a new deposition technique to strengthen the spin-resonator coupling, and benchmark the storage of classical and then quantum fields inside the spin ensemble.
The PhD project will take place in collaboration with a team in ChimieTech synthesizing the CaWO4 crystals, and PStash, a nascent start‑up company based in Paris. The PhD will be funded through an industrial fellowship, and will be realized in Lyon at the beginning with an option to join the experimental effort in Paris at a later stage.
[1] H. J. Kimble, Nature 2008 ; D. Thaker et al.,
ISCA 2006 ; Zaiser et al., Nature Comm 2016
[2] G. Wolfowicz et al., Nature nano (2013).
[3] V. Damon et al., New J. Phys. 13 (2011).
[4] A. Tiranov, arXiv:2504.01592
[5] Kubo et al., PRL 2011

Where to apply

E-mail [e-mail]

Requirements

Research Field Physics » Quantum mechanics Education Level Master Degree or equivalent

Languages ENGLISH Level Excellent

Research Field Physics » Quantum mechanicsPhysics » Solid state physics Years of Research Experience None

Additional Information

Selection process