Tags - (16) quantum metrology

Department(s)/lab(s): School of Physics | Berengut Atomic Structure and Clocks Theory Group @ UNSW
Summary:

Berengut works on the atomic structure theory underpinning next-generation clocks: highly charged ions, whose optical transitions are both extremely narrow and exceptionally sensitive to variation of fundamental constants and to new physics, and the thorium-229 nuclear clock. He identifies which ionic species and transitions maximise sensitivity to the physics of interest while remaining experimentally accessible, and computes the many-body structure needed to interpret them — work that has directly guided the experimental HCI clock programmes at PTB, MPIK and NIST. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — clocks and magnetometers are the two great classes of quantum sensor; his work is on the frequency side of the same estimation problem that fixes pT/sqrt(Hz) performance on the magnetic side. Theory PI with close experimental collaborations.

Department(s)/lab(s): School of Physics | Quantum Control Laboratory @ USyd
Summary:

Biercuk's Quantum Control Laboratory sits precisely at the intersection of control engineering and precision measurement. The group uses trapped ytterbium ions — including large 2D Penning-trap crystals — as both quantum simulators and as calibrated sensors, and is best known for noise spectroscopy: using the qubit itself as a spectrum analyser of its environment, then designing dynamical-decoupling and open-loop control sequences that null the dominant noise. That programme produced Q-CTRL, his quantum control software company, and more recently a serious push into quantum sensing for navigation (magnetic anomaly navigation, quantum-enhanced RF sensing) as a commercial and defence application. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — his filter-function and noise-spectroscopy formalism is now standard equipment in the NV community for designing the DEER and dynamical-decoupling sequences that deliver pT/sqrt(Hz) sensitivity; a candidate from that background would find the theoretical toolkit immediately familiar. Large, well-funded group with strong industry pathways.

Department(s)/lab(s): School of Physics | Chantler X-ray and Precision Atomic Physics Group @ UMelb
Summary:

Chantler's group is built around the idea that X-ray measurements can be made accurate, not just precise: the X-ray Extended Range Technique (XERT) delivers absolute absorption coefficients at the 0.02 per cent level, which in turn allows XAFS to be used for quantitative structure determination and allows high-accuracy tests of atomic theory. The second thread is precision X-ray spectroscopy of highly charged ions and exotic atoms as a test of bound-state QED, where discrepancies between theory and experiment remain unresolved. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — this is precision measurement at the other end of the electromagnetic spectrum: the methodological common ground with pT/sqrt(Hz) NV ensemble sensing is the obsessive treatment of systematics and absolute calibration that separates a sensitive measurement from an accurate one. Borderline inclusion, kept because the group's core competency is metrology rather than X-ray applications.

Department(s)/lab(s): School of Physics | Combes Quantum Measurement Theory Group @ UMelb
Summary:

Combes is a theorist of continuous quantum measurement, quantum trajectories, quantum-limited amplification and quantum filtering, with a strong record of working directly alongside superconducting-circuit and optical experiments rather than in isolation. Recent directions include the fundamental limits of amplifier-based sensing, error-corrected and adaptive metrology protocols, and characterisation/verification of noisy quantum devices. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — his work supplies the estimation-theoretic scaffolding — quantum Fisher information, back-action limits, adaptive protocols — that determines whether an NV ensemble running DEER or nanoscale NMR at pT/sqrt(Hz) is actually operating at its fundamental bound or leaving sensitivity on the table. Theory PI, but explicitly experiment-facing.

Department(s)/lab(s): School of Physics | Quantum Theory Group @ USyd
Summary:

Doherty is a theorist whose early work established much of the modern framework for continuous quantum measurement and quantum feedback control, and who now works across quantum information theory, error correction and the characterisation of quantum devices. For a sensing candidate the relevant body of work is the measurement/feedback theory: conditional evolution under continuous observation, the role of back-action, and the design of feedback protocols that stabilise a quantum system while extracting information from it. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — the continuous-measurement formalism he helped build is what one uses to ask whether a pT/sqrt(Hz) NV ensemble measurement is saturating its quantum Fisher information bound or merely its shot-noise bound. Borderline inclusion — the current group output is largely quantum computing theory rather than sensing — but retained under the inclusive rubric given the measurement-theory pedigree.

Department(s)/lab(s): School of Physics | UNSW Theoretical Atomic Physics Group (Flambaum) @ UNSW
Summary:

Flambaum is one of the most cited atomic theorists alive and the intellectual source of a large fraction of the modern precision-AMO new-physics programme. His group computes the atomic and molecular structure factors that convert an experimental frequency shift into a bound on new physics: enhancement factors for electron and nuclear EDMs, atomic parity violation, the sensitivity of clock transitions to variation of the fine-structure constant, and — most relevant to quantum sensing — the response of atomic clocks, magnetometers and comagnetometers to ultralight/axion-like dark matter fields. He proposed much of the theory behind using networks of quantum sensors as dark matter detectors. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — his theory is what tells an experimentalist what a pT/sqrt(Hz) magnetometer or a 10^-18 clock actually constrains: without it, a spin-precession measurement is just a number. Theory group; a sensing postdoc would collaborate rather than join.

Department(s)/lab(s): Physics | Quantum Optics and Laser Science Group @ Imperial
Summary:

Kim's theoretical group works on quantum optics and quantum information, including generation and application of non-classical light (cat states, GKP states) for quantum metrology, continuous-variable quantum information and fundamental tests of quantum mechanics.

Department(s)/lab(s): Physics | SYRTE - Optical Frequency Metrology Team @ CNRS
Summary:

Le Targat co-leads SYRTE's Optical Frequency Metrology team, which built and continuously operates two independent strontium optical lattice clocks alongside a mercury lattice clock, comparing them at the 10^-16 to 10^-17 level and to SYRTE's caesium fountain primary standards. This work underpins the prospective redefinition of the SI second on an optical transition and supports frequency-transfer, geodesy and fundamental-physics tests via fiber links to other French metrology laboratories.

Department(s)/lab(s): Mechanical Engineering | Lloyd Group (Quantum Information & Complex Systems Theory) @ MIT
Summary:

PREFERRED. Lloyd is a theorist who derived the fundamental limits of accuracy for quantum sensors, detectors and imagers, and originated 'quantum illumination,' the use of entangled light to enhance target detection in the presence of loss and noise (a precursor to quantum radar/lidar concepts); this theoretical program directly underpins experimental quantum-enhanced sensing and imaging efforts elsewhere in the field.

Department(s)/lab(s): School of Physics | Quantum Theory Group @ USyd
Summary:

Mahmoodian is a quantum-optics theorist working on waveguide QED and photon-photon interactions: how strongly-coupled emitters in a one-dimensional photonic channel generate non-classical photon-number correlations, and how those correlated multi-photon states can be exploited. His most sensing-relevant result is the demonstration that photon-number-correlated states produced by a single emitter can be used for quantum-enhanced metrology and absorption spectroscopy, beating the shot-noise limit with a source that requires no squeezing. He also works on the fundamental limits of quantum-enhanced measurement. Positioned against the established body of NV-ensemble quantum sensing work — DEER, nanoscale NMR and T1 relaxometry protocols operating at pT/sqrt(Hz) field sensitivity — his work belongs to the 'fundamental light physics' arm of the search rather than the spin arm, and it addresses the question directly downstream of pT/sqrt(Hz) ensembles: given a shot-noise-limited readout, what does non-classical light buy you? Theory PI, but tightly coupled to photonics experiments.