76 research outputs found
A scanning probe-based pick-and-place procedure for assembly of integrated quantum optical hybrid devices
Integrated quantum optical hybrid devices consist of fundamental constituents
such as single emitters and tailored photonic nanostructures. A reliable
fabrication method requires the controlled deposition of active nanoparticles
on arbitrary nanostructures with highest precision. Here, we describe an easily
adaptable technique that employs picking and placing of nanoparticles with an
atomic force microscope combined with a confocal setup. In this way, both the
topography and the optical response can be monitored simultaneously before and
after the assembly. The technique can be applied to arbitrary particles. Here,
we focus on nanodiamonds containing single nitrogen vacancy centers, which are
particularly interesting for quantum optical experiments on the single photon
and single emitter level.Comment: The following article has been submitted to Review of Scientific
Instruments. After it is published, it will be found at http://rsi.aip.org
Simple atomic quantum memory suitable for semiconductor quantum dot single photons
Quantum memories matched to single photon sources will form an important
cornerstone of future quantum network technology. We demonstrate such a memory
in warm Rb vapor with on-demand storage and retrieval, based on
electromagnetically induced transparency. With an acceptance bandwidth of
= 0.66~GHz the memory is suitable for single photons emitted by
semiconductor quantum dots. In this regime, vapor cell memories offer an
excellent compromise between storage efficiency, storage time, noise level, and
experimental complexity, and atomic collisions have negligible influence on the
optical coherences. Operation of the memory is demonstrated using attenuated
laser pulses on the single photon level. For 50 ns storage time we measure
\emph{end-to-end efficiency}
of the fiber-coupled memory, with an \emph{total intrinsic efficiency}
. Straightforward technological improvements can
boost the end-to-end-efficiency to ; beyond
that increasing the optical depth and exploiting the Zeeman substructure of the
atoms will allow such a memory to approach near unity efficiency.
In the present memory, the unconditional readout noise level of photons is dominated by atomic fluorescence, and for input pulses
containing on average photons the signal to noise level would
be unity
Single-Photon Storage in a Ground-State Vapor Cell Quantum Memory
Interfaced single-photon sources and quantum memories for photons together
form a foundational component of quantum technology. Achieving compatibility
between heterogeneous, state-of-the-art devices is a long-standing challenge.
We built and successfully interfaced a heralded single-photon source based on
cavity-enhanced spontaneous parametric down-conversion in ppKTP and a matched
memory based on electromagnetically induced transparency in warm Rb
vapor. The bandwidth of the photons emitted by the source is 370 MHz, placing
its speed in the technologically relevant regime while remaining well within
the acceptance bandwidth of the memory. Simultaneously, the experimental
complexity is kept low, with all components operating at or above room
temperature. Read-out noise of the memory is considerably reduced by exploiting
polarization selection rules in the hyperfine structure of spin-polarized
atoms. For the first time, we demonstrate single-photon storage and retrieval
in a ground-state vapor cell memory, with
demonstrating the single-photon character of the retrieved light. Our platform
of single-photon source and atomic memory is attractive for future experiments
on room-temperature quantum networks operating at high bandwidth.Comment: 9 pages, 5 figure
Enhancement of the Zero Phonon Line emission from a Single NV-Center in a Nanodiamond via Coupling to a Photonic Crystal Cavity
Using a nanomanipulation technique a nanodiamond with a single nitrogen
vacancy center is placed directly on the surface of a gallium phosphide
photonic crystal cavity. A Purcell-enhancement of the fluorescence emission at
the zero phonon line (ZPL) by a factor of 12.1 is observed. The ZPL coupling is
a first crucial step towards future diamond-based integrated quantum optical
devices
Reservoir Computing with Delayed Input for Fast and Easy Optimisation
Reservoir computing is a machine learning method that solves tasks using the response of a dynamical system to a certain input. As the training scheme only involves optimising the weights of the responses of the dynamical system, this method is particularly suited for hardware implementation. Furthermore, the inherent memory of dynamical systems which are suitable for use as reservoirs mean that this method has the potential to perform well on time series prediction tasks, as well as other tasks with time dependence. However, reservoir computing still requires extensive task-dependent parameter optimisation in order to achieve good performance. We demonstrate that by including a time-delayed version of the input for various time series prediction tasks, good performance can be achieved with an unoptimised reservoir. Furthermore, we show that by including the appropriate time-delayed input, one unaltered reservoir can perform well on six different time series prediction tasks at a very low computational expense. Our approach is of particular relevance to hardware implemented reservoirs, as one does not necessarily have access to pertinent optimisation parameters in physical systems but the inclusion of an additional input is generally possible
Reservoir Computing with Delayed Input for Fast and Easy Optimization
Reservoir computing is a machine learning method that solves tasks using the response of a dynamical system to a certain input. As the training scheme only involves optimising the weights of the responses of the dynamical system, this method is particularly suited for hardware implementation. Furthermore, the inherent memory of dynamical systems which are suitable for use as reservoirs mean that this method has the potential to perform well on time series prediction tasks, as well as other tasks with time dependence. However, reservoir computing still requires extensive task-dependent parameter optimisation in order to achieve good performance. We demonstrate that by including a time-delayed version of the input for various time series prediction tasks, good performance can be achieved with an unoptimised reservoir. Furthermore, we show that by including the appropriate time-delayed input, one unaltered reservoir can perform well on six different time series prediction tasks at a very low computational expense. Our approach is of particular relevance to hardware implemented reservoirs, as one does not necessarily have access to pertinent optimisation parameters in physical systems but the inclusion of an additional input is generally possible
Reservoir Computing with Delayed Input for Fast and Easy Optimization
Reservoir computing is a machine learning method that uses the response of a dynamical system to a certain input in order to solve a task. As the training scheme only involves optimising the weights of the responses of the dynamical system, this method is particularly suited for hardware implementation. Furthermore, the inherent memory of dynamical systems which are suitable for use as reservoirs mean that this method has the potential to perform well on time series prediction tasks, as well as other tasks with time dependence. However, reservoir computing still requires extensive task dependent parameter optimisation in order to achieve good performance. We demonstrate that by including a time-delayed version of the input for various time series prediction tasks, good performance can be achieved with an unoptimised reservoir. Furthermore, we show that by including the appropriate time-delayed input, one unaltered reservoir can perform well on six different time series prediction tasks at a very low computational expense. Our approach is of particular relevance to hardware implemented reservoirs, as one does not necessarily have access to pertinent optimisation parameters in physical systems but the inclusion of an additional input is generally possible
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