[PDF] Towards Solid State Quantum Repeaters eBook

Author : Kristiaan De Greve
Publisher : Springer Science & Business Media
Page : 159 pages
File Size : 32,59 MB
Release : 2013-04-16
Category : Computers
ISBN : 3319000748

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Towards Solid-State Quantum Repeaters: Ultrafast, Coherent Optical Control and Spin-Photon Entanglement in Charged InAs Quantum Dots summarizes several state-of-the-art coherent spin manipulation experiments in III-V quantum dots. Both high-fidelity optical manipulation, decoherence due to nuclear spins and the spin coherence extraction are discussed, as is the generation of entanglement between a single spin qubit and a photonic qubit. The experimental results are analyzed and discussed in the context of future quantum technologies, such as quantum repeaters. Single spins in optically active semiconductor host materials have emerged as leading candidates for quantum information processing (QIP). The quantum nature of the spin allows for encoding of stationary, memory quantum bits (qubits), and the relatively weak interaction with the host material preserves the spin coherence. On the other hand, optically active host materials permit direct interfacing with light, which can be used for all-optical qubit manipulation, and for efficiently mapping matter qubits into photonic qubits that are suited for long-distance quantum communication.

Author : Daniel Rieländer
Publisher :
Page : 152 pages
File Size : 12,25 MB
Release : 2017
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ISBN :

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This PhD thesis is in the scope of experimental quantum communication. It deals with correlated photon pairs of which one photon is stored in a solid state device, while the other photon is at telecom wavelength. Quantum correlation between a photon at telecom wavelength and a photon stored in a quantum memory is an important resource for future applications like quantum repeaters, allowing the transmission quantum states over long distances. During the first part of this thesis, a novel photon pair source has been developed, based on spontaneous parametric downconversion (SPDC) inside a bow-tie cavity. SPDC is a non-linear process which splits a pump photon sporadically into two correlated photons, called signal and idler photon. The source used in this work has been designed to be compatible with a solid state quantum memory based on a Praseodymium doped crystal, using the atomic frequency comp (AFC) protocol. This material has shown promising properties for classical light storage. However, it features a small storage bandwidth of 4 MHz at 606 nm, which sets stringent requirements for the photons to be stored. To match these requirements the SPDC process takes place inside a bowtie cavity which is resonant with the created signal and idler photons. The difference between storage wavelength and telecom wavelength (1436 nm in our case) leads to widely non-degenerate photon pairs. These double resonance leads to a strong clustering effect, which suppresses a high number of redundant spectral modes. The created photon spectrum is investigated carefully and consists of three clusters with few well separated modes. The width of each mode is around 2 MHz and matches the requirement for the quantum memory. Single mode operation was achieved by placing an additional Fabry-Perot cavity in the idler field at 1436 nm. This resulted in the demonstration of the narrowest photon pairs consisting of a spectral single mode, created by SPDC to date. In the second part of the thesis, heralded single photons at 606 nm were created by the detection of a photon at 1436 nm. These heralded photons were then stored as collective optical excitations in a praseodymium crystal, using the AFC scheme. Non-classical correlation between the heralding photon and the stored and retrieved photons were observed for storage time up to 4 μs, 20 times longer than achieved in previous solid state quantum memory experiments. Further development on the source, led to improved results, including an increase of coincidence count rate by one order of magnitude and a heralding efficiency of 28 %. The single photon nature of the heralded photon was also measured directly by showing strong antibunching of the 606 nm signal field. These improvements made the created photons compatible with the storage in the spin state of the praseodymium level scheme, using the full AFC protocol. That enabled an extended storage time of 11 μs with on demand readout of the stored photon. The last part of the thesis explores another important resource for the distribution of quantum states with a quantum repeater, entanglement between the created photon pairs. Here we show a rather new approach of entanglement, which is well suited for narrow band photons based on frequency bins. We take advantage of the fact that the source naturally creates several energy correlated well separated frequency modes. In order to show the coherent superposition of the frequency modes, we use electro-optical modulators to coherently mix them. We could show high-visibility two-photon interference fringes, a strong indicator for entanglement in the frequency domain. The results presented in this thesis open the door for the demonstration of entanglement between a solid-state spin-wave quantum memory and a photon at telecom wavelength. This represents an important step for the realization of quantum repeaters using solid state resources.

Author :
Publisher :
Page : 17 pages
File Size : 50,12 MB
Release : 2007
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In this project, we have carried out the pioneering work for long-distance quantum communication using atomic ensembles for photon-state storage and for implementation of quantum repeaters. This work was followed by many groups and is now considered as one of the most promising approaches to overcoming photon losses in long-distance quantum communication. Specific highlights include theoretical proposals for quantum repeaters based on atomic ensembles (Nature, 414, 413, 2001), atom-atom correlations mediated by dark-state polaritons (Phys. Rev. Lett., 88, 243602, 2002), generation of stationary pulses of light (Phys. Rev. Lett, 89, 143602, 2002); experimental demonstrations of atomic memory for correlated photon states (Science, 301, 196, 2003), stationary pulses of light (Nature 426, 638, 2003), shaping quantum pulses via atomic memory (Phys. Rev. Lett. 93, 233602, 2004)), and finally realization of two-node quantum network involving generation and storage of single photon pulses in two remote ensembles (Nature, 438, 837, 2005). Finally, we proposed and analyzed a novel method that uses fixed, minimal physical resources to achieve generation and nested purification of quantum entanglement for quantum communication over arbitrarily long distances. In this method, solid-state single photon emitters with two internal degrees of freedom formed by an electron spin and a nuclear spin are used to build intermediate nodes in a quantum channel (Phys. Rev. Lett. 96,070504, 2006). Recently, we have experimentally demonstrated such a node using Nitrogen-Vacancy centers in room temperature diamond lattice (submitted to Science, 2007).

Author : Eric Bersin
Publisher :
Page : 0 pages
File Size : 32,87 MB
Release : 2022
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The past decade has seen tremendous progress towards the development of quantum networks, wherein quantum states are transmitted over long distances for applications in distributed quantum computing, quantum-enhanced metrology, and quantum key distribution. In particular, recent results have demonstrated the fundamental building blocks of "quantum repeaters" --- network nodes containing quantum memories that can store, process, and retransmit photonic qubits. Such repeaters are key to deploying scalable quantum networks that can realize the full range of quantum networking applications. However, work in this area has typically been confined to small numbers of low-yield devices, operating in single laboratory environments. Moving from delicate, proof-of-principle physics experiments to robust, practical systems requires advancements on a number of fronts, ranging from fundamental materials science and qubit development to high-level quantum-compatible communications infrastructures. Here, we pursue a full-stack approach towards deployable quantum networks, specifically with solid-state defect centers as quantum memories. We investigate single qubit registers, studying creation techniques and multi-spin architectures that might enhance qubit performance. Next, we propose architectures at the device and repeater levels for improving the ability of a network to take advantage of high-performance qubits. Finally, we develop the classical infrastructure necessary for realizing quantum networks across real-world fiber links, concluding with a demonstration of photon-to-spin quantum state transfer across a 50 km deployed network in the Boston area. Together, these efforts represent a significant step in realizing scalable, memory-enabled quantum networks.

Author : Mohamed Benyoucef
Publisher : John Wiley & Sons
Page : 910 pages
File Size : 15,83 MB
Release : 2023-05-04
Category : Science
ISBN : 3527837434

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Photonic Quantum Technologies Brings together top-level research results to enable the development of practical quantum devices In Photonic Quantum Technologies: Science and Applications, the editor Mohamed Benyoucef and a team of distinguished scientists from different disciplines deliver an authoritative, one-stop overview of up-to-date research on various quantum systems. This unique book reviews the state-of-the-art research in photonic quantum technologies and bridges the fundamentals of the field with applications to provide readers from academia and industry, in one-location resource, with cutting-edge knowledge they need to have to understand and develop practical quantum systems for application in e.g., secure quantum communication, quantum metrology, and quantum computing. The book also addresses fundamental and engineering challenges en route to workable quantum devices and ways to circumvent or overcome them. Readers will also find: A thorough introduction to the fundamentals of quantum technologies, including discussions of the second quantum revolution (by Nobel Laureate Alain Aspect), solid-state quantum optics, and non-classical light and quantum entanglement Comprehensive explorations of emerging quantum technologies and their practical applications, including quantum repeaters, satellite-based quantum communication, quantum networks, silicon quantum photonics, integrated quantum systems, and future vision Practical discussions of quantum technologies with artificial atoms, color centers, 2D materials, molecules, atoms, ions, and optical clocks Perfect for molecular and solid-state physicists, Photonic Quantum Technologies: Science and Applications will also benefit industrial and academic researchers in photonics and quantum optics, graduate students in the field; engineers, chemists, and computer and material scientists.

Author : Yi Li
Publisher :
Page : 0 pages
File Size : 16,52 MB
Release : 2018
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Quantum communication holds the promise of achieving long-distance secure message transmission by exploiting quantum entanglement between remote locations. Quantum repeaters are indispensable to the realization of quantum networks for long-distance quantum communication. Similar to its classical analogue, a good quantum repeater should be able to compensate channel attenuation with a quantum amplifier, and to combat channel distortion through a quantum equaliser. This quantum repeater should also operate by an efficient and robust protocol. The first part of this project researches the continuous mode operation of a noiseless linear amplifier (NLA). We develop a dynamical model to describe the operation of the nondeterministic NLA in the regime of continuous-mode inputs. Both the quantum scissor based NLA and the photon addition-subtraction based NLA are analysed. Simulation results are also presented to confirm theoretical analysis. The second part proposes two quantum protocols. An atomic ensemble based quantum protocol is developed to generate distributed W-states. These generated distributed W-states could be considered as an entanglement resource between more than two distant nodes and would be useful in quantum communication and distributed quantum computation in the future. We also propose a protocol by which quantum key distribution can be achieved deterministically between multiple nodes.This deterministic quantum key distribution scheme may be used to guarantee secure communication for wireless sensor networks and Internet of Things. The last project analyses distortion of quantum channels and develops physically realisable modules to combat it. The minimum phase channel and non-minimum phase all pass channel are discussed separately.

Author : Katherine Rose Ferguson
Publisher :
Page : 0 pages
File Size : 13,62 MB
Release : 2016
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This thesis investigates an entangled light source with an in-built quantum memory based on the protocol of rephased amplified spontaneous emission (RASE). RASE has promising applications as a building-block of a quantum repeater: a device essential for extending the range of current quantum communication links. To be useful RASE must be able to produce high fidelity non-classical light with high efficiency, and be able to store multimode entanglement for long times. This thesis characterises the RASE source and determines to what degree these requirements can be met. The experimental RASE demonstration was conducted in a rare-earth ion doped crystal. Rare-earth ions provide a particularly promising platform for developing quantum technologies as they possess long coherence times on both the optical and hyperfine transitions. In the RASE protocol an inverted ensemble of two-level atoms amplifies the vacuum fluctuations resulting in amplified spontaneous emission (ASE). This results in entanglement between the output optical field and the collective modes of the amplifying ensemble. The collective atomic state dephases due to the inhomogeneous broadening of the ensemble but this can be rephased using photon echo techniques. When the ensemble rephases, a second optical field, the rephased amplified spontaneous emission (RASE), is emitted and is entangled with the ASE. In this thesis, a modified four-level rephasing scheme is used that allows the single photon signals to be spectrally resolved from any coherent background emission associated with the bright driving fields. In addition, four-level RASE incorporates storage on the long-lived hyperfine ground states. Two experiments are described in this thesis. First, a free-space four-level RASE demonstration using continuous-variable detection. In this experiment the different sources of noise were characterised and low noise operation was shown to be possible. Entanglement of the ASE and RASE was confirmed by violating the inseparability criterion with 98.6% confidence. In addition, entanglement was demonstrated after storage of the collective atomic state on the spin states and RASE was shown to be temporally multimode, with almost perfect distinguishability between two temporal modes demonstrated. The degree of entanglement between the ASE and RASE was limited by the rephasing efficiency, which saturated at 3%. It was determined that distortion of the rephasing pulses as they propagate through the optically thick ensemble was the probable cause of the low efficiency. The second experiment was a preliminary cavity-enhanced RASE demonstration. Theoretically perfect rephasing efficiency can be obtained by placing the crystal in an impedance-matched optical cavity. The initial cavity design showed encouraging evidence of an enhancement in the rephasing efficiency, with a 4-fold improvement over the free-space experiment. Improvements to the cavity design were proposed to allow a further increase in the rephasing efficiency of RASE. In summary, this thesis provides an extensive characterisation of an entangled light source with an in-built quantum memory based on rephasing spontaneous emission from an ensemble of ions. Importantly, the RASE scheme allows generation and storage of entanglement in a single protocol, which holds great promise for the development of integrated quantum networks.

Author : Xavier Fernandez Gonzalvo
Publisher :
Page : pages
File Size : 28,32 MB
Release : 2012
Category :
ISBN :

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[ANGLÈS] Quantum frequency conversion of quantum memory compatible photons to telecom wavelength is a requirement for the implementation of scalable quantum repeaters, a key ingredient for long distance quantum communications in optical bers. In this work we characterize a quantum frequency converter implemented with a non-linear waveguide, meant to be coupled to a rubidium atomic ensemble quantum memory. We show promising results allowing us to work in the quantum regime, being this the first demonstration of quantum frequency conversion with quantum memory compatible photons using a solid state device.