41 research outputs found
Interfacing GHz-bandwidth heralded single photons with a room-temperature Raman quantum memory
Photonics is a promising platform for quantum technologies. However, photon
sources and two-photon gates currently only operate probabilistically.
Large-scale photonic processing will therefore be impossible without a
multiplexing strategy to actively select successful events. High
time-bandwidth-product quantum memories - devices that store and retrieve
single photons on-demand - provide an efficient remedy via active
synchronisation. Here we interface a GHz-bandwidth heralded single-photon
source and a room-temperature Raman memory with a time-bandwidth product
exceeding 1000. We store heralded single photons and observe a clear influence
of the input photon statistics on the retrieved light, which agrees with our
theoretical model. The preservation of the stored field's statistics is limited
by four-wave-mixing noise, which we identify as the key remaining challenge in
the development of practical memories for scalable photonic information
processing
Enhancing multiphoton rates with quantum memories
Single photons are a vital resource for optical quantum information
processing. Efficient and deterministic single photon sources do not yet exist,
however. To date, experimental demonstrations of quantum processing primitives
have been implemented using non-deterministic sources combined with heralding
and/or postselection. Unfortunately, even for eight photons, the data rates are
already so low as to make most experiments impracticable. It is well known that
quantum memories, capable of storing photons until they are needed, are a
potential solution to this `scaling catastrophe'. Here, we analyze in detail
the benefits of quantum memories for producing multiphoton states, showing how
the production rates can be enhanced by many orders of magnitude. We identify
the quantity as the most important figure of merit in this connection,
where and are the efficiency and time-bandwidth product of the
memories, respectively.Comment: Just over 4 pages, 2 figure
Enabling a User-Friendly Visualization of Business Process Models
Abstract. Enterprises are facing increasingly complex business pro-cesses. Engineering processes in the automotive domain, for example, may comprise hundreds or thousands of process tasks. In such a scenario, existing modeling notations do not always allow for a user-friendly pro-cess visualization. In turn, this hampers the comprehensibility of business processes, especially for non-experienced process participants. This paper tackles this challenge by suggesting alternative ways of visualizing large and complex process models. A controlled experiment with 22 subjects provides first insights into how users perceive these approaches. Key words: process visualization, user experiment, visual design
Storage of Light in a Hollow-Core Photonic-Crystal Fibre
We report the storage and retrieval of broadband optical pulses using a Raman interaction in a room-temperature ensemble of cesium atoms confined in a hollow-core photonic-crystal fibre. (C) 2013 Optical Society of Americ
Broadband single-photon-level memory in a hollow-core photonic crystal fibre
Storing information encoded in light is critical for realizing optical buffers for all-optical signal processing(1,2) and quantum memories for quantum information processing(3,4). These proposals require efficient interaction between atoms and a well-defined optical mode. Photonic crystal fibres can enhance light-matter interactions and have engendered a broad range of nonlinear effects(5); however, the storage of light has proven elusive. Here, we report the first demonstration of an optical memory in a hollow-core photonic crystal fibre. We store gigahertz-bandwidth light in the hyperfine coherence of caesium atoms at room temperature using a far-detuned Raman interaction. We demonstrate a signal-to-noise ratio of 2.6:1 at the single-photon level and a memory efficiency of 27 +/- 1%. Our results demonstrate the potential of a room-temperature fibre-integrated optical memory for implementing local nodes of quantum information networks
Entang-bling: Observing quantum correlations in room-temperature solids
Quantum entanglement in the motion of macroscopic solid bodies has implications both for quantum technologies and foundational studies of the boundary between the quantum and classical worlds. Entanglement is usually fragile in room-temperature solids, owing to strong interactions both internally and with the noisy environment. We generated motional entanglement between vibrational states of two spatially separated, millimeter-sized diamonds at room temperature. By measuring strong nonclassical correlations between Raman-scattered photons, we showed that the quantum state of the diamonds has positive concurrence with 98% probability. Our results show that entanglement can persist in the classical context of moving macroscopic solids in ambient conditions. © Published under licence by IOP Publishing Ltd
Quantum memory in an optical lattice
Arrays of atoms trapped in optical lattices are appealing as storage media for photons, since motional dephasing of the atoms is eliminated. The regular lattice is also associated with band structure in the dispersion experienced by incident photons. Here we study the influence of this band structure on the efficiency of quantum memories based on electromagnetically induced transparency (EIT) and on Raman absorption. We observe a number of interesting effects, such as both reduced and superluminal group velocities, enhanced atom-photon coupling, and anomalous transmission. These effects are ultimately deleterious to the memory efficiency, but they are easily avoided by tuning the optical fields away from the band edges
Broadband single-photon-level memory in a hollow-core photonic crystal fibre
Storing information encoded in light is critical for realizing optical buffers for all-optical signal processing and quantum memories for quantum information processing. These proposals require efficient interaction between atoms and a well-defined optical mode. Photonic crystal fibres can enhance light-matter interactions and have engendered a broad range of nonlinear effects; however, the storage of light has proven elusive. Here, we report the first demonstration of an optical memory in a hollow-core photonic crystal fibre. We store gigahertz-bandwidth light in the hyperfine coherence of caesium atoms at room temperature using a far-detuned Raman interaction. We demonstrate a signal-to-noise ratio of 2.6:1 at the single-photon level and a memory efficiency of 27 ± 1%. Our results demonstrate the potential of a room-temperature fibre-integrated optical memory for implementing local nodes of quantum information networks. © 2014 Macmillan Publishers Limited. All rights reserved