arXiv subjects

Jevon J. Longdell

Publications and source records attributed to Jevon J. Longdell.

27 records · Page 2Linked to original sources

arXiv2016

Generation of light with multimode time-delayed entanglement using storage in a solid state spin-wave quantum memory

Here we demonstrate generating and storing entanglement in a solid state spin-wave quantum memory with on-demand read out using the process of rephased amplified spontaneous emission (RASE). Amplified spontaneous emission (ASE), resulting from an inverted ensemble of Pr$^{3+}$ ions doped into a Y$_2$SiO$_5$ crystal, generates entanglement between collective states of the praseodymium ensemble and the output light. The ensemble is then rephased using a four-level photon echo technique. Entanglement between the ASE and its echo is confirmed and the inseparability violation preserved when the RASE is stored as a spin-wave for up to 5 $μ$s. RASE is shown to be temporally multimode with almost perfect distinguishability between two temporal modes demonstrated. These results pave the way for the use of multimode solid state quantum memories in scalable quantum networks.

quant-ph↗

arXiv2016

Coupling erbium spins to a three-dimensional superconducting cavity at zero magnetic field

We experimentally demonstrate the coupling at zero magnetic field of an isotopically pure erbium doped yttrium orthosilicate crystal ($^{167}$Er:YSO) to a three-dimensional superconducting cavity with a $Q$ factor of $10^5$. A tunable loop-gap resonator is used, and its resonance frequency is tuned to observe the hyperfine transitions of the erbium sample. The observed spectrum differs from what is predicted by the published spin Hamiltonian parameters. The narrow cavity linewidth also enables the observation of asymmetric line shapes for these hyperfine transitions. Such a broadly tunable superconducting cavity (from 1.6 GHz to 4.0 GHz in the current design) is a promising device for building hybrid quantum systems.

quant-ph↗

arXiv2015

Coherent frequency up-conversion of microwaves to the optical telecommunications band in an Er:YSO crystal

The ability to convert quantum states from microwave photons to optical photons is important for hybrid system approaches to quantum information processing. In this paper we report the up-conversion of a microwave signal into the optical telecommunications wavelength band using erbium dopants in a yttrium orthosilicate crystal via stimulated Raman scattering. The microwaves were applied to the sample using a 3D copper loop-gap resonator and the coupling and signal optical fields were single passed. The conversion efficiency was low, in agreement with a theoretical analysis, but can be significantly enhanced with an optical resonator.

quant-ph↗

arXiv2014

A magneto-optic modulator with unit quantum effciency

We propose a device for the reversible and quiet conversion of microwave photons to optical sideband photons, that can reach 100% quantum effciency. The device is based on an erbium doped crystal placed in both an optical and microwave resonator. We show that effcient conversion can be achieved so long as the product of the optical and microwave cooperativity factors can be made large. We argue achieving this regime is feasible with current technology and we discuss a possible implementation.

quant-ph↗

arXiv2012

Experimental realization of light with time separated correlations by rephasing amplified spontaneous emission

Amplified spontaneous emission is a common noise source in active optical systems, it is generally seen as being an incoherent process. Here we excite an ensemble of rare earth ion dopants in a solid with a π-pulse, resulting in amplified spontaneous emission. The application of a second π-pulse leads to a coherent echo of the amplified spontaneous emission that is correlated in both amplitude and phase. For small optical thicknesses, we see evidence that the amplified spontaneous emission and its echo are entangled.

quant-ph↗

arXiv2011

Photon echo without a free induction decay in a double-Lambda system

We have characterized a novel photon-echo pulse sequence for a double-$Λ$ type energy level system where the input and rephasing transitions are different to the applied $π$-pulses. We show that despite having imperfect $π$-pulses (associated with large coherent emission due to free induction decay), the noise added is only 0.019$\pm$0.001 relative to the shot noise in the spectral mode of the echo. Using this echo pulse sequence in the `rephased amplified spontaneous emission' (RASE) scheme \cite{Ledingham2010} will allow for generation of entangled photon pairs that are in different frequency, temporal, and potentially spatial modes to any bright driving fields. The coherence and efficiency properties of this sequence were characterized in a Pr:YSO crystal.

quant-ph↗

arXiv2010

Hybrid optical and electronic laser locking using spectral hole burning

We report on a narrow linewidth laser diode system that is stabilized using both optical and electronic feedback to a spectral hole in cryogenic Tm:YAG. The laser system exhibits very low phase noise. The spectrum of the beat signal between two lasers, over millisecond timescales, is either Fourier limited or limited by the -111dBc/Hz noise floor. The resulting laser is well suited to quantum optics and sensing applications involving rare earth ion dopants.

physics.optics↗

arXiv2009

Non-classical photon streams using rephased amplified spontaneous emission

We present a fully quantum mechanical treatment of optically rephased photon echoes. These echoes exhibit noise due to amplified spontaneous emission, however this noise can be seen as a consequence of the entanglement between the atoms and the output light. With a rephasing pulse one can get an "echo" of the amplified spontaneous emission, leading to light with nonclassical correlations at points separated in time, which is of interest in the context of building wide bandwidth quantum repeaters. We also suggest a wideband version of DLCZ protocol based on the same ideas.

quant-ph↗

arXiv2006

Quantum study of information delay in electromagetically induced transparency

Using electromagnetically induced transparency (EIT), it is possible to delay and store light in atomic ensembles. Theoretical modelling and recent experiments have suggested that the EIT storage mechanism can be used as a memory for quantum information. We present experiments that quantify the noise performance of an EIT system for conjugate amplitude and phase quadratures. It is shown that our EIT system adds excess noise to the delayed light that has not hitherto been predicted by published theoretical modelling. In analogy with other continuous-variable quantum information systems, the performance of our EIT system is characterised in terms of conditional variance and signal transfer.

quant-ph↗