PhD in Hybrid Quantum Circuits: Molecular Spins for Microwave Quantum Memory

PhD in Hybrid Quantum Circuits: Molecular Spins for Microwave Quantum Memory

Quick Decision

Can deposited molecular-spin films retain useful millikelvin coherence while coupling sufficiently strongly to a superconducting resonator? This experimental hardware doctorate tests a chemically adjustable molecular platform in place of the fixed material environment of a crystal. The research question is distinctive, and the group has directly relevant spin–microwave work. The practical fit depends on the candidate films, the actual supervision arrangement and clarification of the ambiguous qualification label. Official vacancy.

The full-time post is based at ENS de Lyon's Physics Laboratory, UMR 5672, for 36 months from 1 January 2027, at €2,300 gross/month. Applications close 13 November 2026, 23:59 Paris time. The next useful action is to clarify entry qualifications and supervision while showing evidence of relevant microwave/low-temperature experimental work, not only a general interest in quantum computing.

Research Problem and Doctoral Work

A spin ensemble coupled to a superconducting resonator could store travelling microwave quantum states. Long coherence supports storage duration, while inhomogeneous broadening can allow multiple spectral and temporal modes. The advertised bottleneck is the material–resonator interface: crystal growth fixes spin density, the nuclear environment and geometry. The proposed alternative is a molecular film deposited onto an already fabricated superconducting chip, with synthetic control over the nuclear environment and composition. Drop-casting and spin-coating are named integration approaches, without a prescribed fabrication recipe. Research outline.

The candidate families are perchlorotriphenylmethyl and tetrathiatriarylmethyl/trityl radicals, and lanthanide complexes such as Lu(II) or Yb(III). The advert associates radicals with narrow lines and, after isotopic labelling, addressable nuclear spins; selected lanthanide hyperfine structures offer clock transitions. These are candidate advantages to evaluate, not a claim that all materials already have long coherence in the assembled device.

The doctoral researcher will measure the selected candidates’ coherence at millikelvin temperatures and their coupling to a low-impedance resonator. The aim is a quantitative assessment of whether molecular spins can reach the regime needed for microwave quantum memory. The advert describes these candidates as uncharacterised in that temperature regime; this is an advertised research-gap claim, not an independently exhaustive literature conclusion. A completed quantum memory, universal quantum processor or industrial product is not promised.

The central assessment must connect coherence, ensemble linewidth, collective coupling, resonator loss and read/write bandwidth. A strong signal alone does not prove useful quantum storage. The integration process can alter the environment seen by spins and the microwave device, so a credible plan distinguishes material limitations from device/interface limitations. Sample supply, chemistry collaborators, concentration ranges, memory benchmarks and fallback candidates are not specified. These are useful questions for assessing the project, not listed entry requirements.

School, Field and Training Context

The confirmed research host is the Quantum Circuit Group at ENS de Lyon's Physics Laboratory; the employer is the French national research organisation. The precise registering/awarding institution and doctoral-school route are not named in the vacancy. PHAST ED52 independently lists LPENSL among its associated research units, making it relevant context, but it does not confirm this particular registration. National guidance distinguishes employer, host and degree institution and requires doctoral admission and annual registration. PHAST, framework, admission.

ENS de Lyon is joint 235th overall in QS World University Rankings 2027. This is host-level context, not a quantum-physics subject ranking or evidence of this group's supervision quality. More relevant evidence comes from the school's quantum research portal and the group's real microwave/spin work. The portal identifies Audrey Bienfait, Sylvain Hermelin and Benjamin Huard as group principal investigators and describes quantum education initiatives; it does not assign any of them as the director of this vacancy. QS, school quantum programme, group.

The 36-month contract supports a three-year research period. ENS's historical 2025/26 re-registration document shows ADUM approval by doctoral-school, thesis and laboratory authorities and the institution; its dates and fees must not be copied into a 2027 offer. Confirm the actual registration, annual reviews, scientific/professional training, any teaching duties and arrangements if a thesis extends beyond the salary contract. Historical process, national next steps.

Team Research, Publications and Resource Boundaries

The individual supervisors are not confirmed. The school portal, publication directory and Bienfait's primary ORCID record establish relevant team research, not post-specific mentorship. Earlier rare-earth spin-memory recruitment names Bienfait as contact for a different project; it must not be presented as the current molecular-film offer. Directory, ORCID, earlier proposal.

1. Greggio, Lorriaux, Petrescu, Mirrahimi and Bienfait, 2026, Physical Review A 114, 022615. A mean-field/cascaded quantum model derives time-dependent cavity-linewidth control and bounds for storage and retrieval, including a critical bandwidth beyond which efficiency drops. It shows why useful memory feasibility involves bandwidth and coupling dynamics as well as coherence time. It is theory, not an experimental demonstration of the advertised films. The interpretation is based on the full publisher abstract and bibliography, corroborated by the author's preprint abstract; it does not assess the full paper's methods. Paper.
2. Wen et al., including Huard and Bienfait, 2025, arXiv:2510.19684. The team reports a frequency- and bandwidth-tunable superconducting resonator addressing bismuth donors in silicon at a clock transition, with 450 ms Hahn-echo coherence, RF hyperfine addressing and dynamic bandwidth control. It demonstrates a relevant resonator/spin interface, but the material is a crystalline donor system, not one of the molecular films. This is a preprint; no peer-reviewed publication was verified. The interpretation is limited to the complete abstract. Preprint.
3. Lorriaux, Wen, Bertet, Huard and Bienfait, 2026, arXiv:2610.19180. Cavity-assisted nuclear polarisation uses the radiative relaxation channel of a silicon bismuth-donor ensemble at millikelvin temperatures. The observed gain falls short of the ideal limit because of competing relaxation and collective effects. It highlights ensemble initialisation and relaxation as relevant questions, without proving that the same behaviour or protocol transfers to radicals or lanthanide complexes. Posted 13 October 2026, it is also a preprint with no peer review verified here. The interpretation is limited to the complete abstract. Preprint. The MolEQuBe consortium provides real molecular/rare-earth chemistry, optical/spin spectroscopy and superconducting-device collaboration context; LPENSL is a listed partner. However, its 48-month programme from December 2023 is not proof of funding for this January 2027, 36-month contract, nor proof that its planned demonstrations have all succeeded. Likewise, the vacancy's numerical, nanofabrication and cryogenic tools establish offered capability, not particular cryostat hours, fabrication turnaround or committed molecular samples. Consortium.

Salary, Entry Conditions and Lyon Budget

The advert specifies €2,300 gross monthly, 36 months, 44 annual leave/RTT days, 75% transport-cost coverage and up to €300 sustainable mobility support, subject to conditions. The gross 36-month arithmetic is €82,800 before deductions and without assuming changes. National doctoral-employment guidance supports the salary/contract interpretation; it does not establish net pay, fee exemption or a future uplift. Vacancy, doctoral contract.

Lyon3's student guide suggests €720–€1,100/month plus approximately €1,500 installation costs; UCLy provides a nonbinding comparator of €950/month for Lyon/Annecy. The first range annualises to €8,640–€13,200, but neither source is an ENS doctoral housing quote or 2027 guarantee. Some fee/insurance entries in the Lyon3 guide appear inconsistent or dated, so they are not used as this post's charges. Obtain a realistic housing offer and payroll illustration; gross pay minus a student budget is not disposable income. Registration/CVEC, insurance, deposits, relocation and international onboarding remain to be checked. Lyon3 budget, UCLy comparator.

The qualification summary says “Doctorate” while the contract and subject describe doctoral training. This requires clarification; it should neither be converted into a verified requirement to already hold a PhD nor silently replaced with invented Master's marks or language scores. National admission rules provide a Master's/equivalence framework, while the specific doctoral school assesses the candidate. No nationality restriction was identified in the reviewed advert; confirm the actual international hiring and admission route.

Applicant Fit and Preparation

The advert explicitly expects physical sciences—superconductivity, low temperatures, experimental devices and magnetic resonance—high-frequency microwave engineering and nanofabrication. Operational expectations include microwave-measurement expertise, scientific computing, software engineering with Python and Git, and independence. These are concrete expectations and should not be reduced to “physics interest”. Chemical synthesis is part of the materials context, but personal synthesis expertise is not separately stated as an entry prerequisite.

A strong preparation example would explain one's actual experimental or software contribution, an error budget and how a measured property informs a device decision. Relevant transferable skills include cryogenics, RF instrumentation, nanofabrication and reproducible hardware control/analysis. A purely quantum-algorithm portfolio does not by itself address the advertised work.

Career and Field Context

French and European strategies support quantum computing, sensing, communication and skills development. The French Treasury simultaneously stresses that quantum computers remain prototypes and that technical maturity, commercial adoption and financing are uncertain. That combination supports a research/engineering career context, not an automatic industry boom, job count, salary forecast or project placement guarantee. No quantum-subject ranking or graduate-outcome statistics for this post were verified. French strategy, European strategy, Treasury assessment.

Next Actions and Questions to Verify

Before applying: clarify the “Doctorate” label, actual degree equivalence, grades/languages/materials, named supervisor and formal HDR director, registering/awarding institution and doctoral school. Confirm the deadline and January onboarding timetable.

At interview: ask which molecules and chemistry collaborators are committed, how coherence/linewidth/coupling/loss jointly determine success, what memory threshold is realistic in three years, and how the plan responds if films decohere or load the resonator. Verify cryostat, microwave and nanofabrication access and technical support.

Before accepting: obtain the actual funding source and dates, gross/net payroll explanation, fees/CVEC and housing conditions, training/teaching and supervision allocation, data/code/material ownership, international hosting arrangements and extension contingency. These determine whether the materials–device experiment has the support needed to become a feasible doctorate.

Evidence and Sources

The saved recruitment record does not establish whether applications are still being accepted; confirm the current status on the official page. Paper discussions are limited to the available complete abstracts and bibliographic details; they do not assess full-paper methods or supplementary data.

Project, team and school

• Official molecular-spin hybrid-circuit doctoral vacancy.
• Quantum Circuit Group research programme.
• ENS Lyon quantum research and training portal.
• Quantum Circuit Group publication directory.
• Earlier ENS Lyon spin-memory internship/PhD outline.
• MolEQuBe molecular quantum material consortium.
• PHAST doctoral-school research units.
• ENS Lyon 2025/26 doctoral annual re-registration process.
• QS ENS de Lyon overall ranking.
• Audrey Bienfait ORCID research profile.

Original team papers

• Greggio et al. 2026 optimal absorption/emission spin-ensemble memory.
• Wen et al. 2025 tunable resonator at spin clock transitions.
• Lorriaux et al. 2026 cavity-assisted nuclear polarisation.

Doctoral framework, budget and careers

• National doctoral research frameworks.
• National public-law doctoral contract explanation.
• National PhD admission and annual registration.
• National doctoral next-step guidance.
• Lyon3 student living-budget comparator.
• UCLy Lyon/Annecy living-budget comparator.
• French Treasury quantum-sector maturity analysis.
• European Commission Quantum Europe Strategy.
• French quantum strategy 2026 update.

Known bibliographic details

• Linda Greggio; Tristan Lorriaux; Alexandru Petrescu; Mazyar Mirrahimi; Audrey Bienfait. Optimal absorption and emission of itinerant fields into a spin-ensemble memory. Physical Review A 114:022615, 14 August 2026. Record.
• Yutian Wen; V. Ranjan; T. Lorriaux; D. Vion; B. Huard; A. Bienfait; E. Flurin; P. Bertet. Addressing spins at the clock transitions with a frequency- and bandwidth-tunable superconducting resonator. arXiv:2510.19684, preprint, 22 October 2025. Record.
• Tristan Lorriaux; Yutian Wen; Patrice Bertet; Benjamin Huard; Audrey Bienfait. Cavity-assisted dynamic nuclear polarisation. arXiv:2610.19180, preprint, 13 October 2026. Record.