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Journal articleLeung AC, Melody KSI, Tranter AD, et al., 2022,
Observation of cross phase modulation in cold atom gradient echo memory
, New Journal of Physics, Vol: 24, Pages: 093011-093011<jats:title>Abstract</jats:title> <jats:p>Strong nonlinear interactions between single photons have important applications in optical quantum information processing. Demonstrations of these interactions in cold atomic ensembles have largely been limited to exploiting slow light generated using electromagnetically induced transparency (EIT). However, these EIT implementations have limited achievable phase shifts due to spontaneous emission. Here, we demonstrate and characterize a scheme free from these limitations using gradient echo memory with inferred single photon phase shifts of 0.07 ± 0.02 <jats:italic>μ</jats:italic>rad. Excellent agreement with theoretical modelling was observed. Degradation of memory efficiency was observed for large phase shifts but strategies to overcome that are presented.</jats:p>
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Journal articleVolksen F, Devlin JA, Borchert MJ, et al., 2022,
A high-Q superconducting toroidal medium frequency detection system with a capacitively adjustable frequency range >180 kHz
, REVIEW OF SCIENTIFIC INSTRUMENTS, Vol: 93, ISSN: 0034-6748- Cite
- Citations: 2
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Journal articleZhu YR, Joseph D, Ling C, et al., 2022,
Iterative quantum optimization with an adaptive problem Hamiltonian for the shortest vector problem
, PHYSICAL REVIEW A, Vol: 106, ISSN: 2469-9926- Cite
- Citations: 1
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Journal articleRuberti M, Patchkovskii S, Averbukh V, 2022,
Quantum coherence in molecular photoionization
, PHYSICAL CHEMISTRY CHEMICAL PHYSICS, Vol: 24, Pages: 19673-19686, ISSN: 1463-9076- Cite
- Citations: 6
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Journal articleMaimaris M, Pettipher AJ, Azzouzi M, et al., 2022,
Sub-10-fs observation of bound exciton formation in organic optoelectronic devices
, Nature Communications, Vol: 13, ISSN: 2041-1723Fundamental mechanisms underlying exciton formation in organic semiconductors are complex and elusive as it occurs on ultrashort sub-100-fs timescales. Some fundamental aspects of this process, such as the evolution of exciton binding energy, have not been resolved in time experimentally. Here, we apply a combination of sub-10-fs Pump-Push-Photocurrent, Pump-Push-Photoluminescence, and Pump-Probe spectroscopies to polyfluorene devices to track the ultrafast formation of excitons. While Pump-Probe is sensitive to the total concentration of excited states, Pump-Push-Photocurrent and Pump-Push-Photoluminescence are sensitive to bound states only, providing access to exciton binding dynamics. We find that excitons created by near-absorption-edge photons are intrinsically bound states, or become such within 10 fs after excitation. Meanwhile, excitons with a modest >0.3 eV excess energy can dissociate spontaneously within 50 fs before acquiring bound character. These conclusions are supported by excited-state molecular dynamics simulations and a global kinetic model which quantitatively reproduce experimental data.
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Journal articleLiu X, Wang W, Wright SC, et al., 2022,
The chemistry of AlF and CaF production in buffer gas sources
, JOURNAL OF CHEMICAL PHYSICS, Vol: 157, ISSN: 0021-9606 -
Journal articleTarrant J, Khokhlova M, Averbukh V, 2022,
Interferometry of quantum revivals
, JOURNAL OF CHEMICAL PHYSICS, Vol: 157, ISSN: 0021-9606- Author Web Link
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- Citations: 1
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Journal articleSauvage F, Mintert F, 2022,
Optimal Control of Families of Quantum Gates
, PHYSICAL REVIEW LETTERS, Vol: 129, ISSN: 0031-9007- Cite
- Citations: 4
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Journal articleLi Z-P, Wang Y-T, Yu S, et al., 2022,
Experimental investigation of high-efficiency weak-value amplification of nonunitary evolution
, PHYSICAL REVIEW A, Vol: 106, ISSN: 2469-9926- Cite
- Citations: 3
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Journal articleMa Y, Pace MCC, Kim MS, 2022,
Unifying the sorensen-molmer gate and the milburn gate with an optomechanical example
, Physical Review A: Atomic, Molecular and Optical Physics, Vol: 106, ISSN: 1050-2947The Sørensen-Mølmer gate and Milburn gate are two geometric phase gates, generating nonlinear self-interaction of a target mode via its interaction with an auxiliary mechanical mode, in the continuous- and pulsed-interaction regimes, respectively. In this paper we aim at unifying the two gates by demonstrating that the Sørensen-Mølmer gate is the continuous limit of the Milburn gate, emphasizing the geometrical interpretation in the mechanical phase space. We explicitly consider imperfect gate parameters, focusing on relative errors in time for the Sørensen-Mølmer gate and in phase angle increment for the Milburn gate. We find that, although the purities of the final states increase for the two gates upon reducing the interaction strength together with traversing the mechanical phase space multiple times, the fidelities behave differently. We point out that the difference exists because the interaction strength depends on the relative error when taking the continuous limit from the pulsed regime, thereby unifying the mathematical framework of the two gates. We demonstrate this unification in the example of an optomechanical system, where mechanical dissipation is also considered. We highlight that the unified framework facilitates our method of deriving the dynamics of the continuous-interaction regime without solving differential equations.
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Journal articleSun B, Morozko F, Salter PS, et al., 2022,
On-chip beam rotators, adiabatic mode converters, and waveplates through low-loss waveguides with variable cross-sections.
, Light Sci Appl, Vol: 11Photonics integrated circuitry would benefit considerably from the ability to arbitrarily control waveguide cross-sections with high precision and low loss, in order to provide more degrees of freedom in manipulating propagating light. Here, we report a new method for femtosecond laser writing of optical-fiber-compatible glass waveguides, namely spherical phase-induced multicore waveguide (SPIM-WG), which addresses this challenging task with three-dimensional on-chip light control. Fabricating in the heating regime with high scanning speed, precise deformation of cross-sections is still achievable along the waveguide, with shapes and sizes finely controllable of high resolution in both horizontal and vertical transversal directions. We observed that these waveguides have high refractive index contrast of 0.017, low propagation loss of 0.14 dB/cm, and very low coupling loss of 0.19 dB coupled from a single-mode fiber. SPIM-WG devices were easily fabricated that were able to perform on-chip beam rotation through varying angles, or manipulate the polarization state of propagating light for target wavelengths. We also demonstrated SPIM-WG mode converters that provide arbitrary adiabatic mode conversion with high efficiency between symmetric and asymmetric nonuniform modes; examples include circular, elliptical modes, and asymmetric modes from ppKTP (periodically poled potassium titanyl phosphate) waveguides which are generally applied in frequency conversion and quantum light sources. Created inside optical glass, these waveguides and devices have the capability to operate across ultra-broad bands from visible to infrared wavelengths. The compatibility with optical fiber also paves the way toward packaged photonic integrated circuitry, which usually needs input and output fiber connections.
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Journal articleKanari-Naish LA, Clarke J, Qvarfort S, et al., 2022,
Two-mode Schrodinger-cat states with nonlinear optomechanics: generation and verification of non-Gaussian mechanical entanglement
, QUANTUM SCIENCE AND TECHNOLOGY, Vol: 7, ISSN: 2058-9565- Cite
- Citations: 16
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Journal articleDanilov D, Tran T, Bearpark MJJ, et al., 2022,
How electronic superpositions drive nuclear motion following the creation of a localized hole in the glycine radical cation
, JOURNAL OF CHEMICAL PHYSICS, Vol: 156, ISSN: 0021-9606- Cite
- Citations: 3
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OtherWeckesser P, Thielemann F, Karpa L, et al., 2022,
Feshbach resonances between a single ion and ultracold atoms
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Journal articleGarratt D, Misiekis L, Wood D, et al., 2022,
Direct observation of ultrafast exciton localization in an organic semiconductor with soft X-ray transient absorption spectroscopy
, Nature Communications, Vol: 13, ISSN: 2041-1723The localization dynamics of excitons in organic semiconductors influence the efficiency of charge transfer and separation in these materials. Here we apply time-resolved X-ray absorption spectroscopy to track photoinduced dynamics of a paradigmatic crystalline conjugated polymer: poly(3-hexylthiophene) (P3HT) commonly used in solar cell devices. The π→π* transition, the first step of solar energy conversion, is pumped with a 15 fs optical pulse and the dynamics are probed by an attosecond soft X-ray pulse at the carbon K-edge. We observe X-ray spectroscopic signatures of the initially hot excitonic state, indicating that it is delocalized over multiple polymer chains. This undergoes a rapid evolution on a sub 50 fs timescale which can be directly associated with cooling and localization to form either a localized exciton or polaron pair.
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Journal articleZhao H, Mintert F, Knolle J, et al., 2022,
Localization persisting under aperiodic driving
, PHYSICAL REVIEW B, Vol: 105, ISSN: 2469-9950- Cite
- Citations: 9
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Journal articleSchwickert D, Ruberti M, Kolorenc P, et al., 2022,
Electronic quantum coherence in glycine molecules probed with ultrashort x-ray pulses in real time
, SCIENCE ADVANCES, Vol: 8, ISSN: 2375-2548- Cite
- Citations: 27
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Journal articleChevalier H, Kwon H, Khosla KE, et al., 2022,
Many-body probes for quantum features of spacetime
, AVS Quantum Science, Vol: 4, Pages: 1-10, ISSN: 2639-0213Many theories of quantum gravity can be understood as imposing a minimum length scale the signatures of which can potentially be seen in precise table top experiments. In this work, we inspect the capacity for correlated many-body systems to probe non-classicalities of spacetime through modifications of the commutation relations. We find an analytic derivation of the dynamics for a single mode light field interacting with a single mechanical oscillator and with coupled oscillators to first order corrections to the commutation relations. Our solution is valid for any coupling function as we work out the full Magnus expansion. We numerically show that it is possible to have superquadratic scaling of a nonstandard phase term, arising from the modification to the commutation relations, with coupled mechanical oscillators.
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Working paperSempere-Llagostera S, Patel RB, Walmsley IA, et al., 2022,
Experimentally finding dense subgraphs using a time-bin encoded Gaussian boson sampling device
, Publisher: ArxivGaussian Boson Sampling (GBS) is a quantum computing concept based on drawingsamples from a multimode nonclassical Gaussian state using photon-numberresolving detectors. It was initially posed as a near-term approach aiming toachieve quantum advantage, but several applications have been proposed eversince, such as the calculation of graph features or molecular vibronic spectra,among others. For the first time, we use a time-bin encoded interferometer toimplement GBS experimentally and extract samples to enhance the search fordense subgraphs in a graph. Our results indicate an improvement over classicalmethods for subgraphs of sizes three and four in a graph containing ten nodes.In addition, we numerically explore the role of imperfections in the opticalcircuit and on the performance of the algorithm.
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Working paperSun B, Morozko F, Salter PS, et al., 2022,
On-chip beam rotators, polarizers and adiabatic mode converters through low-loss waveguides with variable cross-sections
, Publisher: ArXivPhotonics integrated circuitry would benefit considerably from the ability toarbitrarily control waveguide cross-sections with high precision and low loss,in order to provide more degrees of freedom in manipulating propagating light.Here, we report on a new optical-fibres-compatible glass waveguide byfemtosecond laser writing, namely spherical phase induced multi-core waveguide(SPIM-WG), which addresses this challenging task with three dimensional on-chiplight control. Precise deformation of cross-sections is achievable along thewaveguide, with shapes and sizes finely controllable of high resolution in bothhorizontal and vertical transversal directions. We observed that thesewaveguides have high refractive index contrast of 0.017, low propagation lossof 0.14 dB/cm, and very low coupling loss of 0.19 dB coupled from a single modefibre. SPIM-WG devices were easily fabricated that were able to perform on-chipbeam rotation through varying angles, or manipulate polarization state ofpropagating light for target wavelengths. We also demonstrated SPIM-WG modeconverters that provide arbitrary adiabatic mode conversion with highefficiency between symmetric and asymmetric non-uniform modes; examples includecircular, elliptical modes and asymmetric modes from ppKTP waveguides which aregenerally applied in frequency conversion and quantum light sources. Createdinside optical glass, these waveguides and devices have the capability tooperate across ultra-broad bands from visible to infrared wavelengths. Thecompatibility with optical fibre also paves the way toward packaged photonicintegrated circuitry, which usually needs input and output fibre connections.
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Journal articleWalter N, Seifert J, Truppe S, et al., 2022,
Spectroscopic characterization of singlet-triplet doorway states of aluminum monofluoride
, JOURNAL OF CHEMICAL PHYSICS, Vol: 156, ISSN: 0021-9606 -
Journal articleJoseph D, Martinez AJ, Ling C, et al., 2022,
Quantum mean-value approximator for hard integer-value problems
, PHYSICAL REVIEW A, Vol: 105, ISSN: 2469-9926- Cite
- Citations: 1
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Journal articleThekkadath G, Sempere-Llagostera S, Bell B, et al., 2022,
Experimental demonstration of Gaussian boson sampling with displacement
, PRX Quantum, Vol: 3, ISSN: 2691-3399Gaussian boson sampling (GBS) is a quantum sampling task in which one has to draw samples from the photon-number distribution of a large-dimensional nonclassical squeezed state of light. In an effort to make this task intractable for a classical computer, experiments building GBS machines have mainly focused on increasing the dimensionality and squeezing strength of the nonclassical light. However, no experiment has yet demonstrated the ability to displace the squeezed state in phase space, which is generally required for practical applications of GBS. In this work, we build a GBS machine that achieves the displacement by injecting a laser beam alongside a two-mode squeezed vacuum state into a 15-mode interferometer. We focus on two new capabilities. Firstly, we use the displacement to reconstruct the multimode Gaussian state at the output of the interferometer. Our reconstruction technique is in situ and requires only three measurement settings regardless of the state dimension. Secondly, we study how the addition of classical laser light in our GBS machine affects the complexity of sampling its output photon statistics. We introduce and validate approximate semiclassical models that reduce the computational cost when a significant fraction of the detected light is classical.
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Journal articleDoppelbauer M, Wright SC, Hofsäss S, et al., 2022,
Hyperfine-resolved optical spectroscopy of the A2Π ← X2Σ+ transition in MgF
, The Journal of Chemical Physics, Vol: 156, ISSN: 0021-9606<jats:p>We report on hyperfine-resolved laser spectroscopy of the A2Π ← X2Σ+ transition of magnesium monofluoride (MgF), relevant for laser cooling. We recorded 25 rotational transitions with an absolute accuracy of better than 20 MHz, assigned 56 hyperfine lines, and determined precise rotational, fine, and hyperfine structure parameters for the A2Π state. The radiative lifetime of the A2Π state was determined to be 7.2(3) ns, in good agreement with ab initio calculations. The transition isotope shift between bosonic isotopologues of the molecule is recorded and compared to predicted values within the Born–Oppenheimer approximation. We measured the Stark effect of selected rotational lines of the A2Π ← X2Σ+ transition by applying electric fields of up to 10.6 kV cm−1 and determined the permanent electric dipole moments of 24MgF in its ground X2Σ+ and first excited A2Π states to be μX = 2.88(20) D and μA = 3.20(22) D, respectively. Based on these measurements, we caution for potential losses from the optical cycling transition due to electric field induced parity mixing in the excited state. In order to scatter 104 photons, the electric field must be controlled to below 1 V cm−1.</jats:p>
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Journal articleSong W, Lim Y, Jeong K, et al., 2022,
Quantum solvability of noisy linear problems by divide-and-conquer strategy
, Quantum Science and Technology, Vol: 7, ISSN: 2058-9565Noisy linear problems have been studied in various science and engineering disciplines. A class of 'hard' noisy linear problems can be formulated as follows: Given a matrix $\hat{A}$ and a vector b constructed using a finite set of samples, a hidden vector or structure involved in b is obtained by solving a noise-corrupted linear equation $\hat{A}\mathbf{x}\approx \mathbf{b}+\boldsymbol{\eta }$, where η is a noise vector that cannot be identified. For solving such a noisy linear problem, we consider a quantum algorithm based on a divide-and-conquer strategy, wherein a large core process is divided into smaller subprocesses. The algorithm appropriately reduces both the computational complexities and size of a quantum sample. More specifically, if a quantum computer can access a particular reduced form of the quantum samples, polynomial quantum-sample and time complexities are achieved in the main computation. The size of a quantum sample and its executing system can be reduced, e.g., from exponential to sub-exponential with respect to the problem length, which is better than other results we are aware. We analyse the noise model conditions for such a quantum advantage, and show when the divide-and-conquer strategy can be beneficial for quantum noisy linear problems.
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Journal articleBarrett TJ, Evans W, Gadge A, et al., 2022,
An environmental monitoring network for quantum gas experiments and devices
, QUANTUM SCIENCE AND TECHNOLOGY, Vol: 7, ISSN: 2058-9565 -
Journal articleWoods FER, Jenkins CA, Jenkins RA, et al., 2022,
Optimised Pre-Processing of Raman Spectra for Colorectal Cancer Detection using High-Performance Computing
, APPLIED SPECTROSCOPY, Vol: 76, Pages: 496-507, ISSN: 0003-7028- Cite
- Citations: 4
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Journal articleZhang C, Zhang C, Cheng L, et al., 2022,
Inner-shell excitation in the YbF molecule and its impact on laser cooling
, Journal of Molecular Spectroscopy, Vol: 386, ISSN: 0022-2852The YbF molecule is a sensitive system for measuring the electron’s electric dipole moment. The precision ofthis measurement can be improved by direct laser cooling of the molecules to ultracold temperature. However,low-lying electronic states arising from excitation of a 4f electron may hinder laser cooling. One set of these ‘‘4fhole’’ states lies below the 𝐴2𝛱1∕2 excited state used for laser cooling, and radiative decay to these intermediatelevels, even with branching ratios as small as 10−5, can be a hindrance. Other 4f hole states lie very close tothe 𝐴2𝛱1∕2 state, and a perturbation results in states of mixed character that are involved in the laser coolingcycle. This perturbation may enhance the loss of molecules to states outside of the laser cooling cycle. Wemodel the perturbation of the 𝐴2𝛱1∕2 state to determine the strength of the coupling between the states, thede-perturbed potential energy curves, and the radiative branching ratios to various vibrational levels of theground state, 𝑋2𝛴+. We use electronic structure calculations to characterize the 4f hole states and the strengthsof transitions between these states and the 𝐴2𝛱1∕2 and 𝑋2𝛴+ states. We identify a leak out of the cooling cyclewith a branching ratio of roughly 5 × 10−4, dominated by the contribution of the ground state configurationin a 4f hole state. Finally, we assess the impact of these results for laser cooling of YbF and molecules withsimilar structure.
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Journal articleWalter N, Doppelbauer M, Marx S, et al., 2022,
Spectroscopic characterization of the a<SUP>3</SUP>Π state of aluminum monofluoride
, JOURNAL OF CHEMICAL PHYSICS, Vol: 156, ISSN: 0021-9606- Cite
- Citations: 5
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Journal articleChacko R, Barik S, Banhatti S, et al., 2022,
Multiphoton ionization and dissociation of polycyclic aromatic hydrocarbon molecules of astrophysical interest
, Physical Review A, Vol: 105, ISSN: 2469-9926
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