Bulletin of the American Physical Society
49th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 63, Number 5
Monday–Friday, May 28–June 1 2018; Ft. Lauderdale, Florida
Session U07: Quantum Optics II |
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Chair: Poul Jessen, University of Arizona Room: Grand D |
Friday, June 1, 2018 8:00AM - 8:12AM |
U07.00001: Rydberg Transitions and Interactions in a High Finesse Optical Cavity Yuanxi Chao, Akbar Jahangiri, James Shaffer We report on our work on Rydberg atom-light interaction inside a high-finesse optical cavity. Rubidium atoms are cooled and trapped in a 3-D magneto-optical trap and then transported into a cavity with a finesse of around 28000 using a focus-tunable lens. The atoms inside the cavity are excited into the Rydberg state via a two-photon transition. Cavity assisted Rydberg electromagnetically induced transparency with a three-peak structure is observed. Using this signal, we estimated the intracavity magnetic and electric fields. By adding an external magnetic field to our Rydberg atom-cavity system, we determined the coherence time to be 7.26 microseconds with the 35S Rydberg state of rubidium [1]. Work at higher principle quantum numbers where Rydberg blockade is relevant will also be presented, including pair interaction calculations that support our results. [1] J. Sheng, Y. Chao, S. Kumar, H. Fan, J. Sedlacek, and J. P. Shaffer, Phys. Rev. A 96, 033813 (2017). [Preview Abstract] |
Friday, June 1, 2018 8:12AM - 8:24AM |
U07.00002: Heisenberg Picture Nonlinear Optics and Vacuum Modes in $\chi^{(2)}$ Processes Justin T. Schultz, Sultan A. Wadood, A. Nick Vamivakas, Carlos R. Stroud, Jr. Many quantum mechanical phenomena such as Casimir forces, spontaneous emission, and the Lamb shift have been attributed to the quantum electromagnetic vacuum. Vacuum fluctuations have even been used to model the quantum efficiency of a detector and explain shot noise in homodyne detection. Several recent experimental results involving nonlinear optical interactions have also been interpreted using vacuum fields. The theory describing these processes relies on an effective Hamiltonian that reduces the effect of the nonlinear medium to one single component of the second-order nonlinear susceptibility. The Hamiltonian leads to the interpretation that the vacuum modes ``seed'' the nonlinear process and are therefore responsible for the observed effects. However, the quantum mechanical nature of the nonlinear medium is not considered. To improve our understanding of these processes, we develop a Heisenberg-picture model of nonlinear optics and show that the interaction of a dipole with its own source field can describe these results without a seeding vacuum field. Our work complements earlier results showing, for example, that spontaneous emission can be explained as resulting from either vacuum fluctuations or radiation-reaction fields based on the choice of operator ordering. [Preview Abstract] |
Friday, June 1, 2018 8:24AM - 8:36AM |
U07.00003: Room-Temperature Photon-Number-Resolved Detection Using A Two-Mode Squeezer Elisha Siddiqui Matekole, Deepti Vaidyanathan, Kenji Wang Arai, Ryan T Glasser, Hwang Lee, Jonathan P Dowling We study the average intensity-intensity correlations signal at the output of a two-mode squeezing device with $|N\rangle\otimes|\alpha\rangle$ as the two input modes. We show that the input photon-number can be resolved from the average intensity-intensity correlations. In particular, we show jumps in the average intensity-intensity correlations signal as a function of input photon-number $N$. Therefore, we propose that such a device may be deployed as photon-number-resolving detector at room temperature with high efficiency. [Preview Abstract] |
Friday, June 1, 2018 8:36AM - 8:48AM |
U07.00004: Generation of $^{87}$Rb-resonant bright twin beams with four-wave mixing Saesun Kim, Alberto Marino Squeezed states of light have found a number of useful applications in quantum-enhanced metrology due to their reduced noise properties. There is a particular interest in generating narrow-band squeezed light on atomic resonance in order to achieve an efficient interaction with atomic ensembles. We generate bright two-mode squeezed states of light, or twin beams, with a non-degenerate four-wave mixing (FWM) process in hot $^{85}$Rb in a double-lambda configuration. Given the proximity of the energy levels in the D1 line of $^{85}$Rb and $^{87}$Rb, we are able to operate the FWM in $^{85}$Rb in a regime that generates two-mode squeezed states in which one mode is on resonance with the D1 $F=2$ to $F'=2$ transition and the other mode is on resonance with the D1 $F=1$ to $F'=1$ transition of $^{87}$Rb. For this configuration, we obtain an intensity difference squeezing level of 3.5 dB. Moreover, the intensity difference squeezing increases to 5.4 dB and 5.0 dB when only one of the modes of the squeezed state is resonant with the either the D1 $F=2$ to $F'=2$ or $F=1$ to $F'=1$ transition, respectively. These resonant quantum correlated twin beams can improve atomic interferometers and will make it possible to entangle two distant atomic ensembles in the continuous variable regime. [Preview Abstract] |
Friday, June 1, 2018 8:48AM - 9:00AM |
U07.00005: Growing of quantum Hall states for Rydberg cavity polaritons Fabian Letscher, Peter Ivanov, Jonathan Simon, Michael Fleischhauer Recently, the creation of photonic Landau levels in a twisted cavity has been demonstrated in Nature 534, 671 (2016). Here we propose a scheme to adiabatically transfer flux quanta in multiples of $3 \hbar$ simultaneously to all cavity photons by coupling the photons through flux-threaded cones present in such cavity setup. The flux transfer is achieved using external light fields with orbital angular momentum and a near-resonant dense atomic medium as a mediator. Furthermore, coupling the cavity fields to a Rydberg state in a configuration supporting electromagnetically induced transparency, fractional quantum Hall states can be prepared. To this end a growing protocol is used consisting of a sequence of flux insertion and subsequent single-photon insertion. We discuss specifically the growing of the bosonic Laughlin state with filling 1/2, where we first repeat the flux insertion twice creating a two quasi-hole excitation. Then, the hole is refilled with exactly one photon using a coherent pump and the Rydberg blockade. [Preview Abstract] |
Friday, June 1, 2018 9:00AM - 9:12AM |
U07.00006: Direct measurement of position-momentum entanglement in bright twin beams Ashok Kumar, Alberto M. Marino Entanglement is a key resource for quantum information processing and quantum metrology. In particular, entangling photons in their position-momentum degrees of freedom not only provides a test for the original Einstein-Podolsky-Rosen paradox but also offers a platform for parallel quantum information processing. Here we show the presence of position-momentum entanglement in bright twin beams of light, with a photon flux of the order of $10^{14}$ photon pairs per second, through measurements with an electron multiplying charge-coupled device (EMCCD) camera. We generate the bright twin beams with a four-wave mixing process in a hot rubidium vapor cell and record images of these beams in the near and far field with an EMCCD camera. These near and far field images provide information about spatial and momentum correlations of the photons, respectively. From the recorded images, we have measured squeezing levels of around 0.5 dB in the near field and 2 dB in the far field. The presence of sub-shot noise correlations in the spatial and momentum degrees of freedom demonstrates the quantum nature of the correlations. [Preview Abstract] |
Friday, June 1, 2018 9:12AM - 9:24AM |
U07.00007: Towards a low noise system for generating entangled photons in orbital angular momentum Nathaniel Ristoff, Andrew Ferdinand, F. Elohim Becerra Orbital angular momentum (OAM) of light can be used to increase the information capacity of a communication channel because it allows for multilevel encoding. In quantum communication, multilevel encoding can be used to increase secret key rates in quantum key distribution, while quantum memories based on atomic ensembles can allow for extending communication to long distances. Photon pairs entangled in OAM modes generated from atomic ensembles are readily compatible with atomic quantum memories. We report on the progress towards developing a source of entangled photons in OAM from atomic ensembles with very low levels of noise, that can in principle allow for characterization and control over the OAM spectrum. This source will be based on a cold ensemble of cesium atoms, for which we will employ a variety of techniques to reduce the levels of noise and improve fidelities in the correlation measurements in OAM such as narrow-band frequency filtering and optimized projective measurements with spatial light modulators. This source of entangled photons in OAM will be used for investigations of quantum correlations in high dimensions and entanglement transfer between photons and atoms. [Preview Abstract] |
Friday, June 1, 2018 9:24AM - 9:36AM |
U07.00008: Robust, single-shot measurements for binary phase-shift keyed coherent state discrimination Matt DiMario, F. Elohim Becerra The discrimination of binary phase-shift keyed (BPSK) coherent states is an integral part of many classical and quantum communication schemes. While complex measurement strategies employing feedback can far surpass the Quantum Noise Limit (QNL) set by a Homodyne measurement, there is also a need for non-adaptive strategies that can be scaled to high bandwidths and incorporated into current and future communication methods. Moreover, all measurement strategies are subject to non-ideal conditions and must be able to overcome realistic noise and imperfections in real-world communication channels while keeping their sensitivity performance. We investigate and experimentally demonstrate a robust, high-sensitivity discrimination strategy for BPSK coherent states that is based on a single, optimized displacement operation in phase space followed by photon counting. Robustness of the discrimination strategy comes from the information gained through a photon number resolving (PNR(m)) measurement, corresponding to projections onto Fock states up to a threshold of ``m'' photons, which characterizes the finite number resolution of realistic detectors. Optimal single shot measurements are compatible with high-bandwidth communication while being able to achieve sensitivities below the QNL under realistic conditions. Our experimental demonstration with a realistic detector and finite photon number resolution, allows the measurement to continually outperform the QNL, adjusted for our detection efficiency. [Preview Abstract] |
Friday, June 1, 2018 9:36AM - 9:48AM |
U07.00009: Photon transport in chiral and bidirectional disordered waveguide QED architectures Imran M. Mirza, John C. Schotland Chiral quantum optics [Nature, 541, 473-480 (2017)] has emerged as a fascinating area to study novel types of light-matter interaction in nanophotonic setups. One such architecture (in which emitters can be strongly coupled to nanophotonic waveguides) is the waveguide QED. Till date, most of the work on photon transport in multi-qubit 1D waveguide QED has focused on periodically placed atomic arrays with symmetric waveguide couplings (the same coupling of emitters to left and right waveguide modes). Thanks to the present advancement in chiral quantum optics, in this talk I'll relax the symmetric coupling condition and discuss the photon transport in chiral and small back reflecting waveguides. Additionally, by considering the disorder in the atomic positions and transition frequencies I'll focus on the formation of localized photonic states under varying degrees of disorder [Phys. Rev. A 96, 053804 (2017)]. [Preview Abstract] |
Friday, June 1, 2018 9:48AM - 10:00AM |
U07.00010: Mirrorless Optical Parametric Oscillation in Cold Atoms Xianxin Guo, Yefeng Mei, Luwei Zhao, Shengwang Du We demonstrated a mirrorless optical parametric oscillator (MLOPO) in laser-cooled $^{85}$Rb atoms with backward four-wave mixing (FWM). Without involving any cavities or spatially distributed linear scatterers, the intrinsic feedback is built up by the backward FWM process with electromagnetically induced transparency (EIT). EIT not only resonantly creates transparency for generated anti-Stokes field but also dramatically enhances the $\chi^{(3)}$ nonlinearity. The pump threshold can be tuned by varying the operating parameters, and we achieved it as low as 15 uW, approaching the lowest record of OPO. The narrowest spectral width of the MLOPO in this work we achieved is 16 kHz for both outputs. For the first time, we observed the transition of photon correlation properties from the biphoton quantum regime (below threshold) to the oscillation regime (above threshold). Our system provides an ideal platform for studying the quantum interactions of MLOPO process in a resonant atomic medium. [Preview Abstract] |
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