We optimize the strength of the Four-Wave Mixing (FWM) in warm 85Rb atoms in a double-ladder scheme to identify the optimal conditions for generating the bi-chromatic intensity squeezing. By optimizing the experimental parameters, such as laser frequency and intensity, cell temperature, beam geometry, etc., we achieved FWM gain up to 1.92 with only modest resonant optical losses, and observed some preliminary evidence of the noise correlations between the amplified probe and generated stokes optical field.
Non-Hermitian optics with parity-time (PT) or anti-parity-time (APT) symmetry with controlled gain and loss has resulted in many interesting phenomena that do not necessarily have corresponding counterparts in conservative systems. If such a system enters quantum region, the gain-loss induced unavoidable Langevin noises does not preserve the symmetry. Here, we demonstrate APT symmetric nonlinear optical four-wave mixing (FWM) without involving gain and loss, and thus no Langevin noises are induced. We show that The APT phase transition across the exceptional point is connected to the generation of two-mode light squeezing: In the APT symmetry broken regime the squeezing factor oscillates and is bounded, while in the APT symmetry region the squeezing factor increase exponentially along propagation direction. We will discuss how to implement this dramatic change of quantum squeezing for precision quantum sensing.
Quantum and optical technologies are emerging as two major research frontiers that could potentially revolutionize computing, communication, and sensing for modern science and engineering. One common foundation for many emerging quantum and optical technologies are the hermiticity of the underlying Hamiltonians, which govern the phases and dynamics of the physical systems. In recent years, significant theoretical and experimental progress has been made to explore symmetry (e.g., parity-time (PT)) protected non-Hermitian physics, which showcases unique properties such as exceptional points, anomalous topological states, etc. Here we showcase two applications enabled by PT-symmetry non-Hermitian dynamics in both classical and quantum optical regions: 1) topological edge mode lasing protected by a non-Hermitian bulk in the synthetic space; 2) quantum squeezing and sensing using cold atoms with anti-PT symmetry.
Quantum state tomography (QST) is a crucial ingredient for almost all aspects of experimental quantum information processing. As an analog of the “imaging” technique in quantum settings, QST is born to be a data science problem, where machine learning techniques, noticeably neural networks, have been applied extensively. We build and demonstrate an optical neural network (ONN) for photonic polarization qubit QST. The ONN is equipped with built-in optical nonlinear activation functions based on electromagnetically induced transparency. The experimental results show that our ONN can determine the phase parameter of the qubit state accurately. As optics are highly desired for quantum interconnections, our ONN-QST may contribute to the realization of optical quantum networks and inspire the ideas combining artificial optical intelligence with quantum information studies.
A high-storage efficiency and long-live quantum memory for photons is an essential component for the information processing in long-distance quantum communication and optical quantum computation. We demonstrated a 78% storage efficiency (SE) of coherent light pulses with a cold atomic medium based on the effect of electromagnetically induced transparency (EIT). We also obtained a large fractional delay of 74 at 50% SE, which is the best record to date. The measured fidelity of the memory is better than 90%. The results suggest the EIT light-matter interface can be readily applied to single-photon quantum states. Our work greatly advances the technology of EIT-based quantum memory for the practical quantum information applications.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.