We present a precision gravimeter based on coherent Bragg diffraction of freely falling cold atoms. Traditionally, atomic gravimeters have used stimulated Raman transitions to separate clouds in momentum space by driving between two internal states. interferometers utilize only single state, and can therefore be less susceptible environmental perturbations. Here we show that atoms extracted from magneto-optical trap using an accelerating optical lattice are suitable source for atom...

Abstract Superradiance (SR) is a cooperative phenomenon which occurs when an ensemble of quantum emitters couples collectively to mode the electromagnetic field as single, massive dipole that radiates photons at enhanced rate. Previous studies on solid-state systems either reported SR from sizeable crystals with least one spatial dimension much larger than wavelength light and/or only close liquid-helium temperatures. Here, we report observation room-temperature superradiance highly...

We demonstrate phase sensitivity in a horizontally guided, acceleration-sensitive atom interferometer with momentum separation of $80\ensuremath{\hbar}k$ between its arms. A fringe visibility 7% is observed. Our coherent pulse sequence accelerates the cold cloud an optical waveguide, inherently scalable route to large and high sensitivity. maintain coherence at due both transverse confinement provided by guide our use $\ensuremath{\delta}$-kick cooling on cold-atom cloud. also construct...

Detecting a single photon without absorbing it is long-standing challenge in quantum optics. All experiments demonstrating the nondestructive detection of make use high quality cavity. We present cavity-free scheme for single-photon detection. By pumping nonlinear medium we implement an interfield Rabi oscillation which leads to $\ensuremath{\sim}\ensuremath{\pi}$ phase shift on weak probe coherent laser field presence signal destroying photon. Our operates with fast intrinsic time scale...

We examine the interaction of a weak probe with $N$ atoms in lambda-level configuration under conditions electromagnetically induced transparency (EIT). In contrast to previous works on EIT, we calculate output state resultant slowly propagating light field while taking into account effects ground dephasing and atomic noise for more realistic model. particular, propose two experiments using slow nonclassical show that properties probe, entanglement squeezing, characterizing quantum field,...

Efficient error estimates for the Trotter product formula are central in quantum computing, mathematical physics, and numerical simulations. However, error's dependency on input state its application to unbounded operators remains unclear. Here, we present a general theory estimation, including higher-order formulas, with explicit dependency. Our approach overcomes two limitations of existing operator-norm literature. First, previous bounds too pessimistic as they quantify worst-case...

We present a quantum multimodal treatment describing electromagnetically induced transparency (EIT) as mechanism for storing continuous-variable information in light fields. Taking into account the atomic noise and decoherences of realistic experiments, we numerically model propagation, storage, readout signals contained sideband amplitude phase quadratures pulse using space methods. An analytical effects predicted by this is then presented. Finally, use benchmarks to examine properties...

We demonstrate the feasibility of levitating a small mirror using only radiation pressure. In our scheme, is supported by tripod where each leg Fabry-Perot cavity. The macroscopic state coherently coupled to supporting cavity modes allowing coherent interrogation and manipulation motion. proposed scheme an extreme example optical spring, mechanical oscillator isolated from environment its frequency can be manipulated solely through fields. model stability system find three-dimensional...

We demonstrate a horizontal, linearly guided Mach Zehnder atom interferometer in an optical waveguide. Intended as proof-of-principle experiment, the utilises Bose-Einstein condensate magnetically insensitive |F=1,mF=0> state of Rubidium-87 acceleration sensitive test mass. achieve modest sensitivity to da = 7x10^-4 m/s^2. Our fringe visibility is high 38% this optically interferometer. observe time-of-flight waveguide over half second, demonstrating utility our guide for future sensors.

We describe a scheme for creating quadrature- and intensity-squeezed atom lasers that do not require squeezed light as an input. The beam becomes due to nonlinear interactions between the atoms in analogue optical Kerr squeezing. develop analytic model of process which we compare detailed stochastic simulation system using phase space methods. Finally show significant squeezing can be obtained experimentally realistic suggest ways increasing tunability

A method to create paired-atom laser beams from a metastable helium atom via four-wave mixing is demonstrated. Radio-frequency outcoupling used extract atoms Bose-Einstein condensate near the center of and initiate scattering between trapped untrapped atoms. The unequal strengths interactions for different internal states allows an energy-momentum resonance which leads creation pairs scattered zero-velocity condensate. resulting are well separated main in two-dimensional transverse profile....

The precise implementation and manipulation of quantum gates is key to extracting advantages from future technologies. Achieving this requires very accurate control over the system. If one has complete knowledge about a Hamiltonian, system possible. However, in real scenarios, there will often be some uncertainty parameters which makes full either difficult or impossible. In paper we consider two model Hamiltonians with continuous parameter that partly unknown. We assess robust...

We develop a scheme to generate number squeezing in Bose-Einstein condensate by utilizing interference between two hyperfine levels and nonlinear atomic interactions. describe the using multimode quantum field model find agreement with simple analytic certain regimes. demonstrate that gives strong for realistic choices of parameters species. The can result noise well below limit, even if initial on system is classical much greater than Poissonian (shot-noise limit) distribution.

We theoretically investigate a scheme to enhance spin squeezing in two-component Bose-Einstein condensate (BEC) by utilizing the inherent mean-field dynamics of condensate. Due asymmetry scattering lengths, two components exhibit density oscillations where they spatially separate and recombine. The effective non-linearity responsible for is increased up three orders magnitude when \cite{treutlein2010}. perform multi-mode simulation system using truncated Wigner method, show that this method...

Precision measurements of gravity can provide tests fundamental physics and are broad practical interest for metrology. We propose a scheme absolute gravimetry using quantum magnetomechanical system consisting magnetically trapped superconducting resonator whose motion is controlled measured by nearby RF-SQUID or flux qubit. By driving the mechanical massive to be in macroscopic superposition two different heights our we predict that interferometry protocol could, subject systematic errors,...

We have used the Hanbury Brown-Twiss effect to directly compare density correlations of a pulsed atom laser and ultracold thermal source metastable helium. It was found that isotropic RF outcoupling atoms from Bose-Einstein condensate does not result in decoherence, while 'bunching' typical incoherent sources observed for atoms. This new method significantly increases data acquisition rates compared previous measurements, also permits future novel experiments which may allow us probe...

Entangled resources enable quantum sensing that achieves Heisenberg scaling, a quadratic improvement on the standard limit, but preparing large $N$ spin entangled states is challenging in presence of decoherence. We present control strategy using highly nonlinear geometric phase gates which can be used for generic state or unitary synthesis Dicke subspace with $O(N)$ $O({N}^{2})$ gates, respectively. The method uses dispersive coupling spins to common bosonic mode and does not require...

The possibility of using a solid medium to store few-photon laser pulses as coupled excitations between light and matter is investigated. role inhomogeneous broadening nonadiabaticity are considered, conditions governing the feasibility scheme derived. merits number classes examined.

The traversal of an elliptically polarized optical field through a thermal vapor cell can give rise to rotation its polarization axis. This process, known as self-rotation (PSR), has been suggested mechanism for producing squeezed light at atomic transition wavelengths. We show results the characterization PSR in isotopically enhanced rubidium-87 cells, performed two independent laboratories. observed that, contrary earlier work, presence noise overwhelms observation squeezing. present...

The coherence properties of amplified matter waves generated by four-wave mixing (FWM) are studied using the Hanbury-Brown-Twiss method. We examine two limits. In first case stimulated processes lead to selective excitation a pair spatially separated modes, which we show be second order coherent, while occurs when FWM process is multimode, due spontaneous scattering events leads incoherent waves. Amplified promising candidate for fundamental tests quantum mechanics where correlated modes...