RETRACTED: A room-temperature single-photon source based on strongly interacting Rydberg atoms

Ripka, Fabian; Kübler, Harald; Löw, Robert; Pfau, Tilman

doi:10.1126/science.aau1949

Cited by 169 publications

(99 citation statements)

References 40 publications

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“…To this end, we introduce a second laser field which couples the two ground states. As expected for several waves interacting with a nonlinear medium, this gives rise to a new radiation field via an optical wave mixing process [17][18][19][20][21]. Not expected, however, is that if the laser field coupling the atomic ground states is weak enough, the fragile dark states of the cavity EIT system are not destroyed, even when all fields are on resonance with the respective atomic transitions.…”

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confidence: 94%

Continuous Generation of Quantum Light from a Single Ground-State Atom in an Optical Cavity

et al. 2020

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We show an optical wave-mixing scheme that generates quantum light by means of a single three-level atom. The atom couples to an optical cavity and two laser fields that together drive a cycling current within the atom. Weak driving in combination with strong atom-cavity coupling induces transitions between the dark states of the system, accompanied by single-photon emission and suppression of atomic excitation by quantum interference. For strong driving, the system can generate coherent or Schrödinger cat-like fields with frequencies distinct from those of the applied lasers.Many scientific and technological advances during the last decades, across diverse areas of human knowledge, can be associated to the manipulation of light-matter interaction and the generation of light fields in particular. One such achievement is the laser [1]. Here a photon stimulates an atom to decay into the ground state at the expense of the emission of another photon. To amplify this process, the emitting medium (atoms) is placed inside an optical resonator where the repeated reflection of the light allows for a sufficiently strong coupling between the atoms and the field [2]. By decreasing the volume of the optical resonator it is possible to reach a regime where a single atom and a single photon interact strongly, forming an atom-photon molecule. This establishes the research field known as cavity quantum electrodynamics (cavity QED) [3][4][5][6][7][8][9] where the atom-light interaction is controlled at its most fundamental level. Integrating the phenomenon of electromagnetically induced transparency (EIT) [10-12] adds additional capabilities such as allowing an opaque cavity QED system to become transparent [13][14][15][16]. The origin of this effect lies in the destructive interference of different absorption paths, preventing light from being absorbed by the system. We exploit this situation with a three-level atom in a Λ-type level configuration (one excited and two ground states) where one branch is strongly coupled to a mode of an optical resonator and the other to an external laser. In the EIT regime, the system remains in a state known as a dark state, since the atom does not absorb light from the fields.Here we show that this scheme can be used to continuously generate light that is genuinely quantum in nature. To this end, we introduce a second laser field which couples the two ground states. As expected for several waves interacting with a nonlinear medium, this gives rise to a new radiation field via an optical wave mixing process [17][18][19][20][21]. Not expected, however, is that if the laser field coupling the atomic ground states is weak enough, the fragile dark states of the cavity EIT system are not destroyed, even when all fields are on resonance with the respective atomic transitions. We then find that the two lasers in combination with the cavity drive transitions between dark states that differ by one photon in the cavity. Thus, the atomic excitation is suppressed due to the destructive interference of the EI...

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confidence: 94%

Continuous Generation of Quantum Light from a Single Ground-State Atom in an Optical Cavity

et al. 2020

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“…Rydberg systems consisting of atoms with a highly excited electron [1] have attracted a lot of interest in recent years through studying a variety of quantum manybody [2][3][4], quantum information [5,6], quantum simulation [7,8], and polaron [9] problems. Rydberg atoms in the blockade regime, in particular, are expected to become important tools for quantum information as the manipulation of the entanglement of two or more atoms in these systems are very feasible [10,11].…”

Section: Introductionmentioning

confidence: 99%

Rotons and Bose condensation in Rydberg-dressed Bose gases

et al. 2020

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We investigate the ground-state properties and excitations of Rydberg-dressed bosons in both three and two dimensions, using the hypernetted-chain Euler-Lagrange approximation, which accounts for correlations and thus goes beyond the mean field approximation. The short-range behavior of the pair distribution function signals the instability of the homogeneous system towards the formation of droplet crystals at strong couplings and large soft-core radius. This tendency to spatial density modulation coexists with off-diagonal long-range order. The contribution of the correlation energy to the ground-state energy is significant at large coupling strengths and intermediate values of the soft-core radius while for a larger soft-core radius the ground-state energy is dominated by the mean-field (Hartree) energy. We have also performed path integral Monte Carlo simulations to verify the performance of our hypernetted-chain Euler-Lagrange results in three dimensions. In the homogeneous phase, the two approaches are in very good agreement. Moreover, Monte Carlo simulations predict a first-order quantum phase transition from a homogeneous superfluid phase to the quantum droplet phase with face-centered cubic symmetry for Rydberg-dressed bosons in three dimensions.arXiv:1905.01643v2 [cond-mat.quant-gas]

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“…Increasing the light intensity typically causes further broadening due to saturation or other powerbroadening mechanisms, such as inhomogeneous light-shifts. These broadening or dephasing mechanisms are major limiting factors, particularly in the field of quantum optics with atomic ensembles [2][3][4][5][6]. For instance, the coherence time of collective excitations in atomic gasses is often limited by Doppler dephasing, hindering the performance of single-photon sources and memories [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

Power narrowing: counteracting Doppler broadening in two-color transitions

et al. 2019

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Doppler broadening in thermal ensembles degrades the absorption cross-section and the coherence time of collective excitations. In two photon transitions, it is common to assume that this problem becomes worse with larger wavelength mismatch. Here we identify an opposite mechanism, where such wavelength mismatch leads to cancellation of Doppler broadening via the counteracting effects of velocity-dependent light-shifts and Doppler shifts. We show that this effect is general, common to both absorption and transparency resonances, and favorably scales with wavelength mismatch. We experimentally confirm the enhancement of transitions for different low-lying orbitals in rubidium atoms and use calculations to extrapolate to high-lying Rydberg orbitals. These calculations predict a dramatic enhancement of up to 20-fold increase in absorption, even in the presence of large homogeneous broadening. More general configurations, where an auxiliary dressing field is used to counteract Doppler broadening, are also discussed and experimentally demonstrated. The mechanism we study can be applied as well for rephasing of spin waves and increasing the coherence time of quantum memories. Doppler broadening is ubiquitous in atomic and molecular spectroscopy. Atoms and molecules with different thermal velocities experience different Doppler shifts, which broaden the absorption lines and reduce their contrast [1]. Increasing the light intensity typically causes further broadening due to saturation or other powerbroadening mechanisms, such as inhomogeneous light-shifts. These broadening or dephasing mechanisms are major limiting factors, particularly in the field of quantum optics with atomic ensembles [2][3][4][5][6]. For instance, the coherence time of collective excitations in atomic gasses is often limited by Doppler dephasing, hindering the performance of single-photon sources and memories [7-9]. As Doppler broadening is an inhomogeneous dephasing mechanism, one can potentially counteract it by introducing additional velocity-dependent shifts [10][11][12][13][14]. Here we study the counteraction of Doppler broadening by velocity dependent light-shifts and identify an important class of systems where such counteraction occurs naturally, without a need for additional auxiliary fields.Coherent two-photon processes, such as Raman transitions, two-photon absorption, and electromagnetically induced transparency (EIT), are at the heart of many quantum-optics protocols, ranging from quantum light sources and memories [15][16][17][18] to sensing and quantum nonlinear optics [19]. The canonical example of a three-level system employed for these processes is the Λ configuration, where two longlived ground states are coupled via an intermediate excited state. In these systems, two-photon transitions are usually characterized by negligible residual Doppler broadening, as the nearly-degenerate transition wavelengths experience opposite Doppler shifts [20]. Particularly in a degenerate Λ system under EIT conditions, atoms at all velocities cont...

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RETRACTED: A room-temperature single-photon source based on strongly interacting Rydberg atoms

Cited by 169 publications

References 40 publications

Continuous Generation of Quantum Light from a Single Ground-State Atom in an Optical Cavity

Continuous Generation of Quantum Light from a Single Ground-State Atom in an Optical Cavity

Rotons and Bose condensation in Rydberg-dressed Bose gases

Power narrowing: counteracting Doppler broadening in two-color transitions

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