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Journal articleJae J, Lee J, Kim MS, et al., 2026,
Author Correction: Contextual quantum metrology (npj Quantum Information, (2024), 10, 1, (68), 10.1038/s41534-024-00862-5)
, Npj Quantum Information, Vol: 12Correction to: npj Quantum Informationhttps://doi.org/10.1038/s41534-024-00862-5, published online 04 July 2024 In the original article, the authors followed the standard criterion for estimation precision based on the observed Fisher information. However, the data structure of the contextual quantum metrology (coQM) framework is constructed from an operational quasiprobability model, which does not coincide with the sampling distribution of the measurements
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Journal articleDonnelly L, Klee T, Broughton JJ, et al., 2026,
High-harmonic generation in solids directly driven by a MHz high-power commercial fiber laser
, Optics Express, Vol: 34, Pages: 38314-38314<jats:p> Solid high-harmonic generation (sHHG) is a compact method for producing deep-ultraviolet and vacuum-ultraviolet (VUV) radiation at wavelengths near or below 200 nm. Generally, sHHG relies on ultrashort laser pulses (10–50 fs) at modest repetition rates (kHz) for sub-10 W average power. Here, we demonstrate VUV generation driven by a 50 W, turnkey, MHz-repetition-rate Yb-fiber laser with a pulse duration of ∼0.5 ps. We investigate the optimum material based on the detected 5th harmonic (H5 = 206 nm) flux with a 1.25 MHz driver, and find the following order: <jats:italic toggle="yes">α</jats:italic> -SiO <jats:sub>2</jats:sub> > MgO > <jats:italic toggle="yes">α</jats:italic> -Al <jats:sub>2</jats:sub> O <jats:sub>3</jats:sub> > ZnO > CaF <jats:sub>2</jats:sub> . However, at an average power of 50 W, MgO performs best, yielding an H5 photon flux of ∼10 <jats:sup>10</jats:sup> photons/s. The most stable high-power operation was at 20 W, with an H5 and H7 flux of 7.1 × 10 <jats:sup>9</jats:sup> and 5.2 × 10 <jats:sup>8</jats:sup> photons/s, and RMS fluctuations of 0.80% and 1.14%, respectively. </jats:p>
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Journal articleAlonso-Garcia B, Manresa-Nalda MM, Alexander OG, et al., 2026,
Optimisation of measurement and data analysis of time-resolved X-ray absorption spectroscopy of thin film organic semiconductors.
, Faraday DiscussTime-resolved X-ray absorption spectroscopy (TR-XAS) at X-ray free-electron lasers enables element-specific probing of ultrafast dynamics, but soft X-ray measurements are often limited by low fluorescence yield, strong shot-to-shot fluctuations, and radiation damage in organic thin films. Here, we present a unified framework combining analytical signal-to-noise ratio (SNR) modelling with regression-based analysis for fluorescence-detected soft X-ray absorption spectroscopy. The SNR model predicts fundamentally different optimal conditions for static and transient measurements, with transient experiments requiring thin films (∼80-100 nm) and substantially higher photon counts. We apply this framework to shot-resolved total fluorescence yield XAS measurements of the non-fullerene acceptor Y6 at the nitrogen K-edge using a high-repetition-rate XFEL source, comparing low-dose and intermediate-dose regimes relevant to transient and static measurements, respectively. A calibration-based flux reconstruction systematically improves the fluorescence-flux correlation, while the dominant improvement arises from reformulating XAS extraction as a shot-resolved regression problem. Compared to the conventional ratio-of-means estimator, the regression-based estimator reduces the run-to-run spectral variability by up to a factor of ∼4.4 in the low-dose regime most relevant for transient measurements. Residual-based outlier rejection was found to systematically degrade reproducibility, indicating that the tails of the shot distribution primarily reflect intrinsic XFEL fluctuations rather than detector artefacts. These results demonstrate that reliable soft X-ray TR-XAS requires the joint optimisation of experimental design and statistical inference, providing a practical framework for extracting robust observables from low-signal XFEL measurements in dose-limited regimes.
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Journal articleBressanini G, Ma Y, Hanks M, et al., 2026,
Continuous-time noise mitigation in analogue quantum simulation
, Nature Communications, ISSN: 2041-1723Analogue quantum simulators offer a promising route to explore quantum many-body dynamics beyond classical reach in the near term. However, their vulnerability to noise limits the accuracy of simulations. Here, we establish a continuous-time framework for mitigating noise in analogue quantum simulation. Our protocol fully preserves the continuous-time nature by avoiding any active control or measurement of the system during the dynamics, while achieving exact noise cancellation. This requires a small number of ancillary qubits, whose interaction with the system, combined with classical post-processing of joint measurement data, is tailored to cancel the effect of noise. Furthermore, the protocol is Hamiltonian-independent and robust to realistic ancilla noise. This work points to a promising direction for achieving high-fidelity analogue quantum simulation in the presence of noise.
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Journal articleSchirman E, Ling C, Mintert F, 2026,
Efficient lattice Hamiltonian encoding for the shortest vector problem
, Physical Review Research, ISSN: 2643-1564The advent of quantum computing necessitates the transition of worldwide cryptosystems to post-quantum cryptography (PQC), which is founded upon the problem of finding short vectors in high-dimensional structured lattices. It is assumed that the structure of these lattices cannot be exploited by quantum or classical algorithms attempting to find short vectors. In this work,we focus on the structure of the lattices used in PQC protocols — nega-cyclic (and cyclic) lattices — and provide a quantum algorithmic framework that efficiently encodes the structured lattices into Hamiltonians by exploiting their underlying symmetries. The efficient encoding substantiallyreduces the dimension of the corresponding Hilbert space by limiting it to a relevant subspace where short vectors are likely to be found — leading to significant savings in quantum resources (e.g. qubit count and circuit depth) required to implement a quantum algorithm for finding short vectors. We analytically prove the efficient encoding procedure and benchmark the proposed framework using the variational quantum eigensolver, demonstrating improved results with reduced quantum resources.
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Journal articleSchirman E, Ling C, Mintert F, 2026,
Efficient lattice Hamiltonian encoding for the shortest vector problem
, Physical Review Research, ISSN: 2643-1564 -
Journal articleWalker T, Marchant AL, Bentine E, et al., 2026,
A high-flux source of cold strontium with a loading rate of 4×1010 atoms/s for open release
, Avs Quantum Science, Vol: 8We present a high-flux source of cold strontium atoms based on a two-dimensional magneto-optical trap (2D MOT) and a Zeeman slower. We use the source to load a 3D MOT in a separate science chamber, observing a loading rate of 4 × 10<sup>10</sup> atoms / s—to our knowledge, the highest reported loading flux for strontium. To characterize the vacuum pressure in the science chamber, we load the atoms into a magnetic trap and measure a lifetime of between 8 and 24 s, depending on the oven temperature. Finally, we characterize the atom flux and velocity distributions from the oven and from the 2D MOT source, finding reasonable agreement with models in the free molecular flow regime. Our results show that it is possible to readily produce a cold strontium flux at comparable levels to those of alkali species, at oven temperatures compatible with long-term operation, and at vacuum pressures suitable for state-of-the-art quantum experiments. We make our design available at no cost to benefit researchers in the quantum community.
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Journal articleDriver T, Guo Z, Isele E, et al., 2026,
Attosecond response of molecules to impulsive ionization
, Nature Physics, Vol: 22, Pages: 1459-1466, ISSN: 1745-2473When matter interacts with energetic radiation it can undergo sudden, or impulsive, ionization. This process can drive chemical change and occurs widely in space and planetary atmospheres, yet its comprehensive description challenges our current theoretical and computational capabilities as it requires advanced treatment of electron correlation and nonadiabatic dynamics beyond the Born–Oppenheimer approximation. Here we measure the response of the para-aminophenol molecule to sudden ionization. Using attosecond X-ray absorption spectroscopy, we resolve the ultrafast dynamics of the ionized molecule with atomic precision. A subfemtosecond decay corresponds to states undergoing non-radiative decay, whereas few-femtosecond oscillatory signatures are associated with electronic wavepacket motion in stable cation states that later couple to nuclear motion. We compare our measurement with state-of-the-art computational modelling, qualitatively reproducing the observed response across multiple timescales. These results provide a benchmark for computational models of sudden ionization and ultrafast charge motion in matter.
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Journal articleLeonhardt M, Morgner J, Abbass F, et al., 2026,
Road transport of trapped antiprotons.
, Nature, Vol: 657, Pages: 906-911Low-energy antiprotons confined in ultrahigh-vacuum Penning traps1 enable precision investigations of charge, parity and time-reversal (CPT) invariance2 to test the fundamental symmetry between matter and antimatter. These studies are driven by the search for physics beyond the standard model of particle physics, including efforts to explain the observed cosmological matter-antimatter asymmetry. Until now, such experiments have only been possible at CERN's Antimatter Factory3,4. At present, magnetic-field fluctuations caused by the facility operation limit the sensitivity of trapped-antiproton precision measurements5, which provide the most stringent matter-antimatter symmetry tests in the baryon sector6-9. This has inspired us to develop the cryogenic, open and transportable Penning-trap system BASE-STEP5,10, designed to relocate antiprotons into low-noise offline laboratories, a strategy expected to enable at least 100-fold improved CPT tests9,11. Here we demonstrate the road transport of antiprotons trapped in BASE-STEP. Ninety-two trapped antiprotons have been transported outside the Antimatter Factory along a 7.5-km route without particle loss or measurable degradation of the trap vacuum. This achievement marks the starting point for a new era of antiproton precision measurements8,12 in dedicated low-noise offline laboratory environments.
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Journal articleLowe D, Kim MS, Bondesan R, 2026,
Assessing quantum advantage for Gaussian process regression
, npj Quantum Information, ISSN: 2056-6387Gaussian Process Regression is a machine learning technique with established applications for which several quantum algorithms have been proposed. We showhere that in a wide range of scenarios these algorithms show no exponential speedup. We achieve this by rigorously proving that the condition number of a kernel matrix scales at least linearly with the matrix size under general assumptions on the data and kernel. We additionally prove that the sparsity and Frobenius norm of a kernel matrix scale linearly under similar assumptions. Our results give similar conclusions for kernel ridge regression and quantum support vector machines under the same assumptions. The implications for the quantum algorithms runtime are independent of the complexity of loading classical data on a quantum computer and also apply to dequantised algorithms. We supplement our theoretical analysis with numerical verification for popular kernels in machine learning.
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Journal articleLi Y, Vezzoli S, Klee T, et al., 2026,
Ultrafast switching of optical properties in a doped semiconductor by intense femtosecond laser pulses
, Light: Science & Applications, Vol: 15, ISSN: 2095-5545The rapid switching of materials when excited by ultrashort pulses of light is central for many optical technologies, and in particular to the developing field of time-varying metamaterials. These out-of-equilibrium interactions are difficult to capture with traditional theoretical models. Here we combine experiments and theory to unravel different regimes of interactions and a response saturation for a 44 fs, near-infrared pump pulse exciting a switchable doped semiconductor indium tin oxide thin film target. We model this process as a change in plasma frequency due to the excitation of hot electrons in a non-parabolic conduction band, which increases their effective mass. Our calculations show that saturation at high pump intensities arises because the pump heavily depopulates electrons from below the Fermi level. Excellent agreement with values extracted from experimental data confirms our model. For lower pump intensities, a two-temperature model is consistent with our data, but at higher intensities, it is apparent that other processes are at work, which we attribute to Auger transitions from the valence band, which introduce complex structure into the response, due to non-equilibrium rearrangement of energy between electrons and holes.
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Journal articleBressanini G, Kim M, Kwon H, et al., 2026,
Quantum observables over time for information recovery
, Physical Review Research, Vol: 8, ISSN: 2643-1564We introduce the concept of quantum observables over time (QOOT), an operator that jointly describes two observables at two distinct time points, as a dual of the quantum state over time formalism. We provide a full characterization of the conditions under which a QOOT can be properly defined, via a no-go theorem. We use QOOTs to establish a notion of time-reversal for generic quantum channels with respect to a reference observable, enabling the systematic construction of recovery maps that preserve the latter. These recovery maps, although generally non-physical, can be decomposed into realizable channels, enabling their application in noiseless expectation value estimation tasks. We provide explicit examples and compare our protocol with other error mitigation methods. We show that our protocol retrieves the noiseless expectation value of the reference observable and can achieve optimal sampling overhead, outperforming probabilistic error cancellation.
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Journal articleBrown DJ, Hoogerland MD, 2026,
Quench dynamics and thermalization constraints in a spin–orbit–coupled Bose gas
, New Journal of Physics, Vol: 28We experimentally investigate the quench dynamics of a spin–orbit–coupled (SOC) Bose–Einstein condensate and its subsequent thermalization. We measure the damping of momentum oscillations and find that the damping rate increases with SOC strength. Comparing the observed damping to theoretical estimates of spin drag in the absence of SOC, we find comparable order-of-magnitude scales, establishing a reference for dissipative processes involving thermal atoms. We emphasize that this comparison provides a baseline rather than a quantitative description of the SOC system. In addition, we directly measure the final temperature after relaxation and observe a decrease with increasing coupling strength. These results provide experimentally constrained benchmarks for finite-temperature theories of non-equilibrium dynamics in SOC quantum gases.
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Journal articleRademacher M, Pontin A, Gosling JMH, et al., 2026,
Roto-translational levitated optomechanics
, Physics Reports, Vol: 1187, Pages: 1-66, ISSN: 0370-1573 -
Journal articleJenkins RA, Ziemba MT, Collings FJ, et al., 2026,
Spin Interferometry in a Beam of Ultracold Molecules.
, Phys Rev Lett, Vol: 136We describe a spin interferometer using ultracold YbF molecules and develop the complete set of techniques needed to measure the electron's electric dipole moment, d_{e}, with this apparatus. The molecules are cooled in an optical molasses and prepared in a single internal quantum state. A Raman transition prepares a spin superposition that evolves in parallel magnetic and electric fields before a second Raman transition maps the phase onto the populations of two hyperfine states. These populations are read out using detectors that have spatial and temporal resolution and approach unit efficiency. We characterize the efficiencies and fidelities of all these steps and evaluate the sensitivity of this approach to measuring d_{e}.
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Journal articleDevlin J, Wojtkowiak ML, Banhatti SR, et al., 2026,
A Penning trap single-photon counter for axion detection
, Physical Review Research, ISSN: 2643-1564Discovering the microscopic composition of dark matter is one of the most important open problems in physics today. Axions are a leading candidate to be dark matter; however, a search of the full range of all likely axion masses is hampered by the standard quantum noise limit. This makeshaloscope searches for axions with masses above ∼100 µeV unfeasible with current technologies. To overcome this limitation, we propose a new photon counting technique designed to operate at 30-60 GHz for detecting axions with masses between 124 µeV and 248 µeV, based on a single electron in a Penning trap. The electron cyclotron mode absorbs microwave photons, and, via the continuous Stern-Gerlach effect, this absorption imparts a measurable phase shift onto the axial motion. In this paper, we comprehensively analyze this photon detection method. We introduce a new type of fast, phase-sensitive axial detection technique, using axial-magnetron parametric amplification to overcome detector Johnson noise and cancel associated frequency shifts. This method may find other applications in precision Penning trap frequency measurements. We compare the efficiency of the electron single-photon counter with an ideal device, and find that our proposed photon counter has sufficient performance to search for high mass axions.
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Journal articleBroughton JJ, Allegre H, Marangos JP, et al., 2026,
Beyond the plateau: a phenomenological review of the cutoff in solid high harmonic generation
, Jphys Photonics, Vol: 8Solid high-harmonic generation (sHHG) has emerged as a powerful platform for generating coherent ultraviolet (UV) and extreme-UV radiation and for probing ultrafast electron dynamics in condensed matter. Central to both applications is the high-harmonic cutoff energy, which defines the maximum photon energy attainable and encodes information on the interplay between strong-field driving conditions and the electronic structure of the generating medium. Unlike in gases, where the cutoff follows a well-established ponderomotive scaling, the solid-state cutoff arises from a complex combination of band structure, multiband coupling, carrier dynamics, and propagation effects, and no universal scaling law has yet been established. In this Topical Review, we synthesise the current experimental and theoretical understanding of the cutoff in sHHG, spanning microscopic electron–hole dynamics, intraband and interband emission mechanisms, and their manifestation in plateau formation and spectral extension. We examine how the cutoff scales with driving field strength, wavelength, polarisation, and crystal orientation, and discuss the role of multiband trajectories, Bloch oscillations, and electron dynamics. We further review how macroscopic factors, including absorption, phase matching, propagation, and laser-induced damage, constrain the observable cutoff, often limiting spectral extension even when higher-energy emission is generated microscopically. Strategies for extending the cutoff are assessed, including tailored driving fields, nanostructured and metasurface targets, low-dimensional materials, and band-structure engineering via strain, defects, and doping. Finally, we discuss the spectroscopic significance of the cutoff region, highlighting its sensitivity to band dispersion, ultrafast carrier dynamics, and light-induced electronic structure. By consolidating these perspectives, this review clarifies the mechanisms that govern cutoff formation and identifies the key
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Journal articleLyu Q, Tarbutt M, 2026,
Trapping and cooling mechanisms in blue-detuned magnetooptical traps of molecules
, Physical Review Research, Vol: 8, ISSN: 2643-1564In red-detuned magneto-optical traps (MOTs) of molecules, sub-Doppler heating competes with Doppler cooling, resulting in high temperature and low density. A solution is offered by the blue-detuned MOT where sub-Doppler cooling dominates and the cloud is compressed. Several blue-detuned molecular MOTs have been implemented. A recent implementation relies on a pair of orthogonally polarized components whose frequency separation is smaller than the transition linewidth. We identify the trapping force in these MOTs. At a certain magnetic field, there is a state that is dark to the laser propagating in one direction, but not to the counter-propagating one. This Zeeman-induced dark state (ZIDS) sets up an imbalance in the photon scattering rate, leading to a restoring force. We also study the role of the moving lattices generated by the closely-spaced frequency components of the light. We show that there is a velocity-dependent force that drives the molecules towards the speeds of these moving lattices, and that over a relevant range of magnetic fields this combines with the ZIDS force to transport molecules towards the centre of the MOT. Here, gray molasses cooling, assisted by non-adiabatic transitions driven by the time-varying polarization of the light field, cools the molecules towards zero velocity. We study these mechanisms for model systems with simple level structures, then extend them to molecules with ground state hyperfine structure.
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Journal articleKukreja P, Agarwal P, Doppelbauer M, et al., 2026,
Continuous thermochemical sources of AlF molecules
, New Journal of Physics, Vol: 28The AlF molecule, currently subject to laser cooling and trapping efforts, has the advantage that it can be efficiently produced in a thermochemical reaction between sublimated aluminum trifluoride and aluminum metal. Here we present a series of experiments with continuous molecular beam sources of AlF, utilizing this reaction. We demonstrate a compact AlF molecular beam oven whose total far-field brightness is (Formula presented) (Formula presented) molecules per steradian per second at 923 K, just below the melting temperature of aluminum metal. The continuous output from the oven begins to exceed the peak brightness of a jet-cooled, ablation-based supersonic AlF source for the (Formula presented) (Formula presented), (Formula presented) (Formula presented) level, and we obtain an excellent signal-to-noise ratio with the oven in pulsed laser ionization spectroscopy experiments. By delivering flux from the oven into a cryogenic Ne buffer gas cell, we lower the rotational temperature of the beam to around 30 K and reduce its most probable forward velocity from 600 m s (Formula presented) (Formula presented) to 200 m s (Formula presented) (Formula presented). In addition, we demonstrate that AlF can be made in a simple dispenser package, and observe that molecules thermalize to the laboratory temperature after colliding with vacuum chamber walls of the experiment. The resulting transient AlF vapor may enable direct loading of a molecular magneto-optical trap.
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Journal articleBaynham CFA, Hobson R, Buchmüller O, et al., 2026,
A prototype differential atom interferometer for fundamental physics.
, Nature, Vol: 654, Pages: 622-628Gravitational waves and ultralight dark matter are among the most compelling frontiers in fundamental physics, motivating proposals for very-long-baseline atom interferometerssuch as AION1, MAGIS2, AICE3 and AEDGE4 that aim to detect at frequencies at which ground-based5 and space-borne6 laser interferometers lose sensitivity. Very-long-baseline atom interferometers look for signals by comparing the quantum phase evolution of widely separated atomic ensembles interrogated by a common laser. However, their performance depends critically on suppressing noise sources, particularly laser phase noise. The experimental validation of such noise rejection remains an important challenge. Here we demonstrate a prototype differential atom interferometer based on the single-photon clock transition of fermionic 87Sr. Thus, we obtain a gradiometer configuration with a species intrinsically suited to kilometre-scale and space-baseline operation. The instrument operates at the standard quantum limit7 with no excess noise beyond atom shot noise. The differential configuration maintains quantum-limited sensitivity in the presence of several radians of artificially injected laser phase noise per shot, which emulates the conditions expected in a very-long-baseline atom interferometer. We also demonstrate the recovery of coherent oscillatory signals across a broad frequency range under fully phase-randomized conditions, a capability that is inaccessible to a single interferometer operating in the same regime. These results provide an experimental validation of the noise-immune measurement principle underlying very-long-baseline atom interferometers and mark an important step towards next-generation quantum sensors for gravitational-wave detection and searches for ultralight dark matter8,9.
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Journal articleFigueiredo JL, Schofield RC, Fu M, et al., 2026,
A quantum kinetic theory of photon Bose-Einstein condensation in semiconductors.
, Rep Prog Phys, Vol: 89Photon condensation in semiconductor microcavities is a transformative technique for engineering quantum states of light at room temperature by tailoring strong but incoherent light-matter interactions. While continuous-wave and electrical pumping offer exceptional prospects for miniaturized quantum photonic technologies, harnessing these requires conceptual advances in understanding non-equilibrium light-matter dynamics in semiconductors. We resolve this challenge through anab initioquantum kinetic theory capturing how Coulomb interactions of optically excited carriers and phonon scattering mediate photon thermalization and condensation in semiconductors. Our microscopic model shows that at high carrier densities, thermalization is dominated by carrier-carrier Coulomb scattering, in clear contrast to the rovibrational relaxation that governs dye-based photon condensates. The theory predicts a rich nonequilibrium phase diagram with thermal, Bose-condensed, multimode, and lasing phases, quantitatively in agreement with recent experiments. Crucially, we identify how cavity detuning controls transitions between equilibrium and gain-dominated regimes, enabling tailored design of coherent light sources. This work thus provides the foundation for semiconductor-based quantum photonic devices operating beyond conventional laser paradigms.
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Journal articleKowalczyk KM, Wyatt AS, Allegre H, et al., 2026,
Strong-field propagation effects in high harmonic generation from MgO
, APL Photonics, Vol: 11High harmonic generation in crystals is a strong-field process that can be used to probe the electronic structure and dynamics of solids and promises a route to attosecond control in the condensed phase. Here, we investigate the complex spatiospectral structures in high harmonics generated from MgO crystals in transmission geometry. We explore the patterns within individual harmonics as a function of laser intensity. Using z-scan analysis, we retrieve the nonlinear refractive index and employ propagation calculations to examine the transverse spatial coherence model, consistent with the interband dominated harmonic emission, as the source of these patterns. We find that the inclusion of the nonlinear propagation effects explains the structures well, without requiring a multi-trajectory interference or changing dephasing times.
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Journal articleHo C, Dutta J, Mukherjee B, et al., 2026,
Tuning interactions between static-field-shielded polar molecules with microwaves
, Physical Review Research, Vol: 8, ISSN: 2643-1564The ability to tune interparticle interactions is one of the main advantages of using ultracold quantum gases forquantum simulation of many-body physics. Current experiments with ultracold polar molecules employ shielding with microwave or static electric fields to prevent destructive collisional losses. The interaction potential ofmicrowave-shielded molecules can be tuned by using microwaves of two different polarizations, while for static-field-shielded molecules the tunability of interactions is more limited and depends on the particular species.In this work, we propose a general method to tune the interactions between static-field-shielded molecules byapplying a microwave field. We carry out coupled-channel scattering calculations in a field-dressed basis set todetermine loss rate coefficients and scattering lengths. We find that both the s-wave scattering length and thedipole length can be widely tuned by changing the parameters of the microwave field, while maintaining strong suppression of lossy collisions.
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Journal articleKnight PL, Raymer M, Vitanov NV, 2026,
EDITORIAL: Celebrating the life and science of Joseph H Eberly
, Journal of Physics B Atomic Molecular and Optical Physics, Vol: 59, ISSN: 0953-4075 -
Conference paperWebber-Date A, Rowley M, Osborn PF, et al., 2026,
A quantum-classical cold atom system for inertial navigation
, ISSN: 0277-786XThe results of a marine trial for a cold atom system for inertial navigation (HARLEQUIN) is presented. The system is a deployable atom interferometer demonstrator for navigation using inertial measurements. The interferometer is a grating based, Mach-Zehnder interferometer using rubidium-87 to make measurements of acceleration in a single axis. The output of the quantum sensor is used to condition classical sensors, in a quantum-classical hybrid measurement scheme. The subsystems of HARLEQUIN have been tested aboard a marine platform operated by the UK General Lighthouse Authority, to determine its performance in marine environments and informing an upgrade path to a fully deployable quantum sensor. Presented are results from the trial and upgrade path towards a fully deployable quantum sensor.
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Journal articleVylegzhanin A, Brown DJ, Abdrakhmanov S, et al., 2026,
Light-induced, fictitious magnetic trapping of cold alkali-metal atoms using an optical-tweezer–nanofiber hybrid platform
, Physical Review A, Vol: 113, ISSN: 2469-9926<jats:p> We present a magnetic trapping scheme for cold <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"> <a:mmultiscripts> <a:mi>Rb</a:mi> <a:mprescripts/> <a:none/> <a:mn>87</a:mn> </a:mmultiscripts> </a:math> atoms based on light-induced fictitious magnetic fields generated by the evanescent field of an optical nanofiber (ONF) integrated with optical tweezers. We calculate and compare the trapping potentials for both Gaussian and Laguerre-Gaussian modes of the tweezer beam, combined with a quasilinearly polarized ONF-guided field. Based on the optical powers in the tweezer and ONF modes, we analyze the trap depths and the positions of the potential minima from the nanofiber surface. We show that, by varying the optical powers in the two fields, the trap position can be tuned over several hundred nanometers while simultaneously influencing the trap depth and trap frequencies. Such control over the atom-surface position is essential for studying distance-dependent effects on atoms trapped near a dielectric surface and optimizing atom-photon interfaces for quantum technology applications. </jats:p>
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Journal articleGwak G, Roh C, Yoon Y-D, et al., 2026,
Completely characterizing multimode second-order nonlinear optical quantum processes
, Nature Photonics, Vol: 20, Pages: 156-162, ISSN: 1749-4885Complete characterization of a multimode optical process has paved the way for understanding complex optical phenomena, leading to the development of novel optical technologies. Until now, however, characterizations have mainly focused on linear optical processes, despite the importance of nonlinear optical processes for photonic technologies. Here we report the complete experimental characterization of multimode second-order nonlinear optical quantum processes—also known as bosonic Gaussian channels. Our resource-efficient characterization method, demonstrated on a 16-mode quantum process, captures the full information of non-unitary quantum evolution and satisfies the required physical condition. This complete characterization enables the identification of eigenquadratures and their associated amplification and noise properties. Moreover, we demonstrate the broad applicability of our method by characterizing various nonlinear optical quantum processes, including cluster-state generation, mode-dependent loss with nonlinear interaction and a quantum noise channel. Our method, by providing a versatile and efficient technique for characterizing a nonlinear optical process, will be beneficial for developing scalable photonic technologies.
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Conference paperLi Z, Zhan H, Winston SH, et al., 2026,
Machine learning of quantum data using optimal similarity measurements
We demonstrate sample-optimal similarity measurements for quantum data with bosonic interference on a programmable photonic processor. This hardware-scalable scheme achieves information-theoretic optimal scaling, providing a building block for efficient quantum machine learning.
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Conference paperMachado GJ, Alwehaibi YK, Thekkadath G, et al., 2026,
Unconditional Sub-Shot-Noise Phase Sensing via Nonlinear Interferometry and Photon-Number-Resolving Detection
We demonstrate unconditional quantum-enhanced phase sensing using nonlinear interferometry and photon-number-resolving detection, exploiting full photon statistics to achieve sub-shot-noise sensitivity without post-selection and establishing a robust route to practical quantum metrology.
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Journal articleYu S, Sun J, Chen KC, et al., 2026,
Extensible universal photonic quantum computing with nonlinearity
, Nature Photonics, ISSN: 1749-4885Universal quantum computing requires an architecture that supports both linear circuits and, crucially, strong nonlinear resources. For quantum photonic systems, integrating such nonlinearities with scalable linear circuitry has been a main bottleneck, leaving most optical experiments without nonlinear operations and, consequently, incapable of achieving universality. Here we report on an extensible photonic computer that supports a universal physical gate set by seamlessly combining fully programmable, scalable linear-optical networks with integrated nonlinear modules. This platform enables a broad range of quantum computing and simulation tasks. We demonstrate the quasi-deterministic generation of optical Gottesman–Kitaev–Preskill states, which are essential resources for bosonic error correction yet had previously been realized only probabilistically. Furthermore, we simulate complex many-body quantum dynamics, exemplified by the Bose–Hubbard model. Such quantum simulation tasks have long been considered beyond the reach of photonic hardware limited to linear operations. These capabilities, enabled by our extensible architecture, establish a viable route towards photonic quantum simulation and fault-tolerant quantum computing.
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