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| Open AccessThermodynamic behavior of correlated electron-hole fluids in van der Waals heterostructures
Transition metal dichalcogenide bilayers offer a novel platform for studying correlated electron-hole fluids. Here the authors use optical spectroscopy to probe thermodynamic properties of coupled electron-hole states in MoSe2/hBN/WSe2 heterostructures, providing evidence for an excitonic insulator ground state.
- Ruishi Qi
- , Andrew Y. Joe
- & Feng Wang
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Article
| Open AccessThe 5α condensate state in 20Ne
Alpha particle clustering plays a significant role in lighter nuclei. Here the authors study the exotic 5α gas-like clustering state of 20Ne, that is 5α condensate state.
- Bo Zhou
- , Yasuro Funaki
- & Taiichi Yamada
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Article
| Open AccessMicrocavity phonoritons – a coherent optical-to-microwave interface
Photonic, electronic and lattice resonances in patterned semiconductor microcavities are tailored to demonstrate coherent bidirectional microwave-to-optical conversion via phonon-exciton-photon quasi-particles in the strong-coupling regime.
- Alexander Sergeevich Kuznetsov
- , Klaus Biermann
- & Paulo Ventura Santos
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| Open AccessObservation of an Alice ring in a Bose–Einstein condensate
An Alice ring is related to the unusual topology of the monopole field and its decay. Here the authors demonstrate a topological monopole defect in the form of an Alice ring using gaseous Bose–Einstein condensates of 87Rb atoms.
- Alina Blinova
- , Roberto Zamora-Zamora
- & David S. Hall
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| Open AccessAsynchronous locking in metamaterials of fluids of light and sound
Exciton-polariton condensates are hybrid systems with nonlinear interactions. Here the authors demonstrate metamaterials with inter-site polariton coupling and asynchronous locking of light fluids from neighbor sites at the energy detuning.
- D. L. Chafatinos
- , A. S. Kuznetsov
- & A. Fainstein
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Article
| Open AccessCollective excitations of a bound-in-the-continuum condensate
Bound-states-in-the-continuum (BICs) display unique features like symmetry protection from dissipation, long lifetimes and topological charges. Here the authors demonstrate anisotropic Bogoliubov excitation spectrum of polariton condensate from a BIC using a patterned semiconductor GaAs/AlGaAs waveguide.
- Anna Grudinina
- , Maria Efthymiou-Tsironi
- & Nina Voronova
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Article
| Open AccessSignature of spin-triplet exciton condensations in LaCoO3 at ultrahigh magnetic fields up to 600 T
Spin-triplet exciton condensation has been predicted in perovskite cobaltites in high magnetic fields. Here, the authors report the magnetic phase diagram of LaCoO3 from magnetostriction measurements in ultrahigh magnetic fields and reveal new high-field phases with signatures of the exciton condensate.
- Akihiko Ikeda
- , Yasuhiro H. Matsuda
- & Joji Nasu
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Article
| Open AccessDouble dome structure of the Bose–Einstein condensation in diluted S = 3/2 quantum magnets
Previous studies of magnetic Bose–Einstein condensates have been limited to magnetic materials with small spin numbers. Here the authors study the magnetic phase diagram of a S = 3/2 quantum antiferromagnet and show a double dome structure that is attributed to different types of condensates.
- Yoshito Watanabe
- , Atsushi Miyake
- & Taka-hisa Arima
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Article
| Open AccessA space-based quantum gas laboratory at picokelvin energy scales
Ultracold ensembles are promising sources for precision measurements when their quantum state can precisely be prepared. Here the authors achieve a quantum state engineering of Bose-Einstein condensates in space using NASA’s Cold Atom Lab aboard the International Space Station making a step forward towards space quantum sensing.
- Naceur Gaaloul
- , Matthias Meister
- & Nicholas P. Bigelow
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Article
| Open AccessVortex dynamics in the two-dimensional BCS-BEC crossover
The crossover between the limiting ground states of fermionic systems, the so called BCS-BEC crossover, is of interest to superconductor and ultracold atomic gases communities. The authors study the dynamics of superconducting vortices in the crossover regime via the Hall response in a 2D superconductor LixZrNCl.
- Max Heyl
- , Kyosuke Adachi
- & Yoshihiro Iwasa
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| Open AccessQuantized topological pumping of solitons in nonlinear photonics and ultracold atomic mixtures
Synthetic lattice systems are powerful platforms for studying the influence of intrinsic nonlinearities on topological phenomena. Here the authors elucidate the topological transport of solitons in terms of Wannier functions displacement and they introduce a nonlinearity-induced topological transport effect that could be observed in ultracold quantum mixtures.
- Nader Mostaan
- , Fabian Grusdt
- & Nathan Goldman
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Article
| Open AccessObservation of Bose-Einstein condensates of excitons in a bulk semiconductor
Bose-Einstein condensate of excitons is expected in photo-excited bulk semiconductors, but a direct experimental evidence has been lacking. Here the authors report the observation of a condensate of 1s paraexcitons in Cu2O using real-space mid-infrared absorption imaging realized in a dilution refrigerator.
- Yusuke Morita
- , Kosuke Yoshioka
- & Makoto Kuwata-Gonokami
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Article
| Open AccessTopological superfluid defects with discrete point group symmetries
Ordinary vortex line defects are well-studied across different physical systems. Here the authors demonstrate, in atomic spinor Bose–Einstein condensates, previously unobserved vortex line defects with discrete polytope symmetries, which are of interest to quantum information applications.
- Y. Xiao
- , M. O. Borgh
- & D. S. Hall
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Article
| Open AccessNonlinear two-level dynamics of quantum time crystals
Recent work has reported a realization of a time crystal in the form of the Bose-Einstein condensate of magnons in superfluid 3He. Here, the authors study the dynamics of a pair of such quantum time crystals and show that it closely resembles the evolution of a two-level system, modified by nonlinear feedback.
- S. Autti
- , P. J. Heikkinen
- & V. B. Eltsov
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Article
| Open AccessSecond sound in the crossover from the Bose-Einstein condensate to the Bardeen-Cooper-Schrieffer superfluid
The second sound is an entropy oscillation propagating with constant pressure. Here the authors demonstrate the variation of the second sound wave in the crossover from the Bose-Einstein condensate to the Bardeen-Cooper-Schrieffer superfluid using 6Li.
- Daniel K. Hoffmann
- , Vijay Pal Singh
- & Johannes Hecker Denschlag
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Article
| Open AccessEvidence for spin current driven Bose-Einstein condensation of magnons
A gas of magnons, quantised magnetic excitations, can be driven into a Bose-Einstein condensation (BEC) state even at room temperature. Here, Divinskiy et al show that it is possible to achieve stationary equilibrium room-temperature magnon BEC via a spin-current.’
- B. Divinskiy
- , H. Merbouche
- & S. O. Demokritov
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Article
| Open AccessLaughlin anyon complexes with Bose properties
The microscopic nature of neutral collective excitation of the fractional quantum Hall state is still debated. Here the authors show that a macroscopic ensemble of neutral excitations in the 1/3 state exhibits properties of a Bose system with an exceptionally long coherence time.
- L. V. Kulik
- , A. S. Zhuravlev
- & V. Y. Umansky
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Article
| Open AccessSpatial coherence of room-temperature monolayer WSe2 exciton-polaritons in a trap
Here, the authors show that the interaction between microcavity photons and excitons in an atomically thin WSe2 results in a hybridized regime of strong light-matter coupling. Coherence build-up is accompanied by a threshold-like behaviour of the emitted light intensity, which is a fingerprint of a polariton laser effect.
- Hangyong Shan
- , Lukas Lackner
- & Carlos Antón-Solanas
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Article
| Open AccessQuantum fluids of light in all-optical scatterer lattices
Semiconductor microcavities allow engineering of artificial lattices with optical write-in and read-out of information. Here, the authors show an optically imprinted system of exciton-polaritons arranged in a Lieb lattice and reveal a nonequilibrium transition from scattered- to trapped polariton condensates.
- S. Alyatkin
- , H. Sigurdsson
- & P. G. Lagoudakis
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| Open AccessTunable exciton-polaritons emerging from WS2 monolayer excitons in a photonic lattice at room temperature
Excitons in atomically thin crystals couple strongly with light. Here, the authors observe lattice polaritons in a tunable open optical cavity at room temperature, with an imprinted photonic lattice strongly coupled to excitons in a WS2 monolayer.
- L. Lackner
- , M. Dusel
- & C. Schneider
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| Open AccessRoom temperature exciton–polariton Bose–Einstein condensation in organic single-crystal microribbon cavities
The use of room temperature exciton–polariton Bose–Einstein condensation is limited by the need for external high-finesse microcavities. The authors generate room temperature EPs with single-crystal microribbons as waveguide Fabry–Pérot microcavities, and demonstrate controllable output of coherent light.
- Ji Tang
- , Jian Zhang
- & Yong Sheng Zhao
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Article
| Open AccessGeometric frustration in polygons of polariton condensates creating vortices of varying topological charge
There is interest in studying vorticity in systems of light-matter interaction using different platforms. Here, the authors show vortices of topological charge more than one and their scaling in an exciton-polariton condensate using GaAs microcavity with embedded InGaAs quantum wells.
- Tamsin Cookson
- , Kirill Kalinin
- & Pavlos G. Lagoudakis
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Article
| Open AccessMoiré pattern of interference dislocations in condensate of indirect excitons
Previous interference experiments on indirect excitons found dislocation-like phase singularities that could not be explained by common phase defects. Here, the authors explain these features in terms of the moiré pattern of interference of condensate matter waves propagating over macroscopic distances.
- J. R. Leonard
- , Lunhui Hu
- & A. C. Gossard
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Article
| Open AccessObservation of two-dimensional Anderson localisation of ultracold atoms
Anderson localization has been previously reported in 1D and 3D but it has remained elusive in 2D environments. Here the authors report probable observation of 2D Anderson localization using ultracold atoms in a weak interaction regime.
- Donald H. White
- , Thomas A. Haase
- & David A. W. Hutchinson
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Article
| Open AccessPolariton condensation and surface enhanced Raman in spherical ZnO microcrystals
Polariton dynamics are usually studied in high quality cavities in semiconductor hetero structures. Here, the authors demonstrate polariton dynamics and surface polariton field enhanced Raman responses in micro-spherical ZnO.
- Victor V. Volkov
- , Daniel J. Oliver
- & Carole C. Perry
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Article
| Open AccessPolariton-driven phonon laser
Efficient generation of phonons is an important ingredient for a prospective electrically-driven phonon laser for coherent control of quantum systems. Here, the authors report on laser-like phonon emission in a hybrid semiconductor microcavity that optomechanically couples BEC polaritons with phonons.
- D. L. Chafatinos
- , A. S. Kuznetsov
- & A. Fainstein
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Article
| Open AccessSynthetic band-structure engineering in polariton crystals with non-Hermitian topological phases
To simulate band structures of solid state materials synthetic lattices are usually generated by optical lattices or by irreversible patterning the system. Here, the authors present reconfigurable synthetic band-structures in optical exciton-polariton lattices and generate non-Hermitian topological phases.
- L. Pickup
- , H. Sigurdsson
- & P. G. Lagoudakis
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Article
| Open AccessSub-picosecond thermalization dynamics in condensation of strongly coupled lattice plasmons
Understanding the sub-picosecond dynamics of driven-dissipative condensates of interacting bosons is challenging. Here the authors combine a lattice of plasmonic nanoparticles with a dye molecule solution in strong coupling and reveal distinct lasing, stimulated thermalization, and condensation regimes.
- Aaro I. Väkeväinen
- , Antti J. Moilanen
- & Päivi Törmä
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| Open AccessRoom temperature organic exciton–polariton condensate in a lattice
Many studies of polariton condensates have been limited to low temperatures. Here the authors demonstrate ambient polariton condensation in lattices using organic traps that profit from the stability of organic excitons and the large Rabi splitting.
- M. Dusel
- , S. Betzold
- & C. Schneider
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| Open AccessDirect evidence of spatial stability of Bose-Einstein condensate of magnons
Little is known about the underlying mechanism responsible for the spatial stability of magnon Bose-Einstein condensates. Here experimental evidence is provided for a repulsive interaction of magnons in the condensate resulting in its stabilization.
- I. V. Borisenko
- , B. Divinskiy
- & S. O. Demokritov
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| Open AccessNon-stationary statistics and formation jitter in transient photon condensation
Description of non-equilibrium phase transitions is problematic, due to the absence of suitable free energy landscapes. Here, the authors experimentally show delayed photon condensation and timing jitter in a dye-filled microcavity, modelled by a non-equilibrium extension of the free-energy landscape.
- Benjamin T. Walker
- , João D. Rodrigues
- & Robert A. Nyman
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Article
| Open AccessRealization of all-optical vortex switching in exciton-polariton condensates
Vortices can be generated in many platforms and are useful due to manipulation of their vorticity. Here the authors show generation and optical switching of a vortex in exciton-polariton condensates using GaAs microcavities.
- Xuekai Ma
- , Bernd Berger
- & Stefan Schumacher
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| Open AccessObservation of quantum depletion in a non-equilibrium exciton–polariton condensate
Many aspects of polariton condensate behaviour can be captured by mean-field theories but interactions introduce additional quantum effects. Here the authors observe quantum depletion in a driven-dissipative condensate and find that deviations from equilibrium predictions depend on the excitonic fraction.
- Maciej Pieczarka
- , Eliezer Estrecho
- & Elena A. Ostrovskaya
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Article
| Open AccessControlled creation of a singular spinor vortex by circumventing the Dirac belt trick
Topological defects and textures are universal phenomena across physics. The authors demonstrate that an initial non-singular spinor texture can be controllably transformed into a pair of singular vortices with cores filled by atoms that continuously connect distinct magnetic phases of matter.
- L. S. Weiss
- , M. O. Borgh
- & D. S. Hall
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| Open AccessBogoliubov waves and distant transport of magnon condensate at room temperature
Exploration of magnon Bose–Einstein condensate (BEC) may enable intriguing applications in magnonic devices. Here the authors show experimentally the condensed magnons forming compact humps of BEC density can propagate many hundreds of micrometers in the form of Bogoliubov waves.
- Dmytro A. Bozhko
- , Alexander J. E. Kreil
- & Burkard Hillebrands
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| Open AccessOut-of-equilibrium quantum magnetism and thermalization in a spin-3 many-body dipolar lattice system
Isolated many-body quantum systems do not thermalize with an external environment but in most cases the internal dynamics leads to the emergence of an effective thermal equilibrium for local degrees of freedom. Here the authors study this behaviour with a realization of a long-range spin model.
- S. Lepoutre
- , J. Schachenmayer
- & B. Laburthe-Tolra
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Article
| Open AccessSpontaneous formation and relaxation of spin domains in antiferromagnetic spin-1 condensates
Order parameter and phase characterization of multicomponent quantum system is of fundamental importance. Here the authors show the parameter control of the dynamics and relaxation of the magnetic ordering of the spin-1 Bose-Einstein condensates of sodium atoms in uniform magnetic field.
- K. Jiménez-García
- , A. Invernizzi
- & F. Gerbier
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Article
| Open AccessBose–Einstein condensation of photons in an erbium–ytterbium co-doped fiber cavity
Bose–Einstein condensates were demonstrated at low temperatures, mostly with ultracold bosonic atoms. Here, the authors demonstrate BEC of photons in a standard 1D erbium–ytterbium co-doped fiber cavity at, below and above room temperature.
- Rafi Weill
- , Alexander Bekker
- & Baruch Fischer
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Article
| Open AccessSpin current generation and relaxation in a quenched spin-orbit-coupled Bose-Einstein condensate
Spin-orbit coupling is interesting for fundamental understanding of spin transport and quench dynamics. Here the authors demonstrate spin-current generation and its relaxation in spin-orbit-coupled Bose-Einstein condensates of Rb atoms in different spin states.
- Chuan-Hsun Li
- , Chunlei Qu
- & Yong P. Chen
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Article
| Open AccessDissipative shock waves generated by a quantum-mechanical piston
There is increasing interest in understanding the non-equilibrium phenomena in quantum fluids. Here, the authors show dissipative, viscous shock and rarefaction wave dynamics emerging from the turbulent, superfluid flow of an elongated BEC of ultracold Rb atoms driven by a quantum-mechanical piston.
- Maren E. Mossman
- , Mark A. Hoefer
- & P. Engels
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Article
| Open AccessRobust quantum valley Hall effect for vortices in an interacting bosonic quantum fluid
Topologically protected pseudospin transport is difficult to implement for bosonic systems due to the lack of symmetry-protected pseudospins. Here, Bleu et al. propose robust valley pseudospin transport, truly topologically protected by the winding of a quantum vortex propagating between two staggered honeycomb lattices.
- O. Bleu
- , G. Malpuech
- & D. D. Solnyshkov
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Article
| Open AccessSingle-shot condensation of exciton polaritons and the hole burning effect
The mechanism for exciton-polariton condensation in the presence of an incoherent reservoir has been long debated. Here the authors demonstrate the role of the spatial hole burning in condensation of long‐lived exciton polaritons by imaging the condensates in a single-shot excitation regime.
- E. Estrecho
- , T. Gao
- & E. A. Ostrovskaya
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Article
| Open AccessExperimental realization of a Rydberg optical Feshbach resonance in a quantum many-body system
Ultracold Rydberg molecules have characteristic properties that can be exploited for quantum control and applications. Here the authors demonstrate a Rydberg optical Feshbach resonance, which is based on ultra-long-range Rydberg molecules.
- O. Thomas
- , C. Lippe
- & H. Ott
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Article
| Open AccessDiffusive and arrested transport of atoms under tailored disorder
Cold atom quantum simulation has had challenges in realising the tailored, dynamic types of disorder relevant to real materials. Here, the authors use synthetic momentum-space lattices to engineer spatially and dynamically controlled disorder to observe ballistic, diffusive, and arrested atomic transport.
- Fangzhao Alex An
- , Eric J. Meier
- & Bryce Gadway
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Article
| Open AccessFirst-order spatial coherence measurements in a thermalized two-dimensional photonic quantum gas
Phase transitions in quantum matter are related to correlation effects and they can change the ordering of material. Here the authors measure the first-order spatial correlation and the de Broglie wavelength for both thermal and condensed form of a photonic Bose gas in a dye-filled optical microcavity.
- Tobias Damm
- , David Dung
- & Julian Schmitt
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Article
| Open AccessObservation of dynamic atom-atom correlation in liquid helium in real space
Liquid helium can be treated as an ideal gas or a condensed liquid and displays intriguing features like Bose–Einstein condensation. Here the authors show that roton excitation reveals information on real space dynamic atom-atom correlations in superfluid helium, which could be used to benchmark models.
- W. Dmowski
- , S. O. Diallo
- & T. Egami
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Article
| Open AccessSupermode-density-wave-polariton condensation with a Bose–Einstein condensate in a multimode cavity
When a single mode optical cavity is coupled to a Bose-Einstein condensate, one usually observes a single mode of light when strongly pumped. Here the authors observe a supermode in the output of a multimode cavity and relate this to a signature of a nonequilibrium condensation phase transition.
- Alicia J. Kollár
- , Alexander T. Papageorge
- & Benjamin L. Lev
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Article
| Open AccessMagnetofermionic condensate in two dimensions
The motion of particles in a quantum condensate state are described by a single macroscopic wave function, leading to a host of unusual properties. Here, the authors generate such a condensation of magnetically induced excitons, known as cyclotron magnetoexcitons, in a high-mobility quantum well.
- L. V. Kulik
- , A. S. Zhuravlev
- & S. Schmult
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Article
| Open AccessGiant superconducting fluctuations in the compensated semimetal FeSe at the BCS–BEC crossover
The crossover between the weak-coupling limit and strong-coupling limit provides important information for quantum bound states of interacting fermions. Here, Kasahara et al. report thermodynamic evidence for prevailing phase fluctuations of superconductivity, highlighting unusual normal state in the BCS-BEC crossover regime.
- S. Kasahara
- , T. Yamashita
- & Y. Matsuda