Journal Article•
Quantum entanglement between an optical photon and a solid-state spin qubit
TL;DR: The reported entanglement source can be used in studies of fundamental quantum phenomena and provides a key building block for the solid-state realization of quantum optical networks.
Abstract: Quantum entanglement is among the most fascinating aspects of quantum theory. Entangled optical photons are now widely used for fundamental tests of quantum mechanics and applications such as quantum cryptography. Several recent experiments demonstrated entanglement of optical photons with trapped ions, atoms and atomic ensembles, which are then used to connect remote long-term memory nodes in distributed quantum networks. Here we realize quantum entanglement between the polarization of a single optical photon and a solid-state qubit associated with the single electronic spin of a nitrogen vacancy centre in diamond. Our experimental entanglement verification uses the quantum eraser technique, and demonstrates that a high degree of control over interactions between a solid-state qubit and the quantum light field can be achieved. The reported entanglement source can be used in studies of fundamental quantum phenomena and provides a key building block for the solid-state realization of quantum optical networks.
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Journal Article•
TL;DR: In this paper, a network of atomic clocks using non-local entangled states is proposed to achieve unprecedented stability and accuracy in time-keeping, as well as being secure against internal or external attack.
Abstract: A proposed network of atomic clocks—using non-local entangled states—could achieve unprecedented stability and accuracy in time-keeping, as well as being secure against internal or external attack.
247 citations
Cites methods from "Quantum entanglement between an opt..."
...The remote entanglement can be implemented by using recently demonstrated techniques for individual atom-photon entanglement [25–29]....
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...[27] Togan, E....
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Journal Article•
TL;DR: In this paper, the authors demonstrate nanometer-precision depth control of nitrogen-vacancy (NV) center creation near the surface of synthetic diamond using an in situ nitrogen delta-doping technique during plasmaenhanced chemical vapor deposition.
Abstract: We demonstrate nanometer-precision depth control of nitrogen-vacancy (NV) center creation near the surface of synthetic diamond using an in situ nitrogen delta-doping technique during plasma-enhanced chemical vapor deposition. Despite their proximity to the surface, doped NV centers with depths (d) ranging from 5 to 100 nm display long spin coherence times, T2 > 100 μs at d = 5 nm and T2 > 600 μs at d ≥ 50 nm. The consistently long spin coherence observed in such shallow NV centers enables applications such as atomic-scale external spin sensing and hybrid quantum architectures.
191 citations
Journal Article•
TL;DR: Milburn et al. as mentioned in this paper demonstrated dispersive, single-spin coupling to light for both nondestructive spin measurement, through the Faraday effect, and coherent spin manipulation, through optical Stark effect.
Abstract: Dressing-Up Diamond Defects The spin states of nitrogen vacancy defects in diamond are being explored as information carriers and memories in quantum information systems. Their long lifetimes, fast manipulation rates, and the ability to couple them to adjacent electronic and nuclear spins provide the necessary properties for implementation in solid-state quantum networks. To date, however, the readout of the spin state via photoluminescence, either directly or indirectly, results in the destruction of the spin state. Buckley et al. (p. 1212, published online 14 October; see the Perspective by Milburn) have formed a light-matter hybrid state in which the spin interacts with laser light to form a polariton state. This hybrid state can be optically probed to produce a nondestructive measurement and manipulation technique for the spin state of the nitrogen-vacancy center. Optical pulses were used to nondestructively probe and manipulate the spin state of nitrogen vacancy defects in diamond. The exceptional spin coherence of nitrogen-vacancy centers in diamond motivates their function in emerging quantum technologies. Traditionally, the spin state of individual centers is measured optically and destructively. We demonstrate dispersive, single-spin coupling to light for both nondestructive spin measurement, through the Faraday effect, and coherent spin manipulation, through the optical Stark effect. These interactions can enable the coherent exchange of quantum information between single nitrogen-vacancy spins and light, facilitating coherent measurement, control, and entanglement that is scalable over large distances.
161 citations
Journal Article•
TL;DR: Optically levitated a nanodiamond in partial vacuum and demonstrated electron spin control of its built-in nitrogen-vacancy centers and the strength of electron spin resonance is enhanced when the air pressure is reduced.
Abstract: Electron spins of diamond nitrogen-vacancy (NV) centres are important quantum resources for nanoscale sensing and quantum information. Combining NV spins with levitated optomechanical resonators will provide a hybrid quantum system for novel applications. Here we optically levitate a nanodiamond and demonstrate electron spin control of its built-in NV centres in low vacuum. We observe that the strength of electron spin resonance (ESR) is enhanced when the air pressure is reduced. To better understand this system, we investigate the effects of trap power and measure the absolute internal temperature of levitated nanodiamonds with ESR after calibration of the strain effect. We also observe that oxygen and helium gases have different effects on both the photoluminescence and the ESR contrast of nanodiamond NV centres, indicating potential applications of NV centres in oxygen gas sensing. Our results pave the way towards a levitated spin–optomechanical system for studying macroscopic quantum mechanics. Hybrid systems coupling electron spins and optomechanical responses are of potential use in quantum information systems and sensing technology. Here, the authors demonstrate optical levitation of nanodiamonds and the control of their nitrogen vacancy spins in vacuum.
66 citations
Journal Article•
TL;DR: In this article, the emission of single photons from a single Er^{3+} ion in a solid-state host, whose optical transition at 1.5 µm is in the telecom band, allowing for low-loss propagation in optical fiber.
Abstract: Single atoms and atomlike defects in solids are ideal quantum light sources and memories for quantum networks. However, most atomic transitions are in the ultraviolet-visible portion of the electromagnetic spectrum, where propagation losses in optical fibers are prohibitively large. Here, we observe for the first time the emission of single photons from a single Er^{3+} ion in a solid-state host, whose optical transition at 1.5 μm is in the telecom band, allowing for low-loss propagation in optical fiber. This is enabled by integrating Er^{3+} ions with silicon nanophotonic structures, which results in an enhancement of the photon emission rate by a factor of more than 650. Dozens of distinct ions can be addressed in a single device, and the splitting of the lines in a magnetic field confirms that the optical transitions are coupled to the electronic spin of the Er^{3+} ions. These results are a significant step towards long-distance quantum networks and deterministic quantum logic for photons based on a scalable silicon nanophotonics architecture.
45 citations
References
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TL;DR: This special issue of Mathematical Structures in Computer Science contains several contributions related to the modern field of Quantum Information and Quantum Computing, with a focus on entanglement.
Abstract: This special issue of Mathematical Structures in Computer Science contains several contributions related to the modern field of Quantum Information and Quantum Computing.
The first two papers deal with entanglement. The paper by R. Mosseri and P. Ribeiro presents a detailed description of the two-and three-qubit geometry in Hilbert space, dealing with the geometry of fibrations and discrete geometry. The paper by J.-G.Luque et al. is more algebraic and considers invariants of pure k-qubit states and their application to entanglement measurement.
14,205 citations
"Quantum entanglement between an opt..." refers background in this paper
...The entangled state given by equation (1) is created because photon polarization is uniquely correlated with the final spin state....
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...On detection of a linearly polarized jHæ or jVæ photon at time td, the entangled state in equation (1) is projected to + j i~ 1ffiffi 2 p z1 j i+ {1 j i ð Þ, respectively....
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TL;DR: In this paper, the authors proposed a method for quantum interconnects, which convert quantum states from one physical system to those of another in a reversible manner, allowing the distribution of entanglement across the network and teleportation of quantum states between nodes.
Abstract: Quantum networks provide opportunities and challenges across a range of intellectual and technical frontiers, including quantum computation, communication and metrology. The realization of quantum networks composed of many nodes and channels requires new scientific capabilities for generating and characterizing quantum coherence and entanglement. Fundamental to this endeavour are quantum interconnects, which convert quantum states from one physical system to those of another in a reversible manner. Such quantum connectivity in networks can be achieved by the optical interactions of single photons and atoms, allowing the distribution of entanglement across the network and the teleportation of quantum states between nodes.
5,003 citations
TL;DR: In this paper, the authors consider the atomic dynamics and the optical response of the medium to a continuous-wave laser and show how coherently prepared media can be used to improve frequency conversion in nonlinear optical mixing experiments.
Abstract: Coherent preparation by laser light of quantum states of atoms and molecules can lead to quantum interference in the amplitudes of optical transitions. In this way the optical properties of a medium can be dramatically modified, leading to electromagnetically induced transparency and related effects, which have placed gas-phase systems at the center of recent advances in the development of media with radically new optical properties. This article reviews these advances and the new possibilities they offer for nonlinear optics and quantum information science. As a basis for the theory of electromagnetically induced transparency the authors consider the atomic dynamics and the optical response of the medium to a continuous-wave laser. They then discuss pulse propagation and the adiabatic evolution of field-coupled states and show how coherently prepared media can be used to improve frequency conversion in nonlinear optical mixing experiments. The extension of these concepts to very weak optical fields in the few-photon limit is then examined. The review concludes with a discussion of future prospects and potential new applications.
4,218 citations
TL;DR: In this article, the linear-polarization correlation of pairs of photons emitted in a radiative cascade of calcium has been measured using two-channel polarizers (i.e., optical analogs of Stern-Gerlach filters).
Abstract: The linear-polarization correlation of pairs of photons emitted in a radiative cascade of calcium has been measured. The new experimental scheme, using two-channel polarizers (i.e., optical analogs of Stern-Gerlach filters), is a straightforward transposition of Einstein-Podolsky-Rosen-Bohm gedankenexperiment. The present results, in excellent agreement with the quantum mechanical predictions, lead to the greatest violation of generalized Bell's inequalities ever achieved.
2,408 citations
TL;DR: Here, it is demonstrated the synthesis and application of ultrapure isotopically controlled single-crystal chemical vapour deposition (CVD) diamond with a remarkably low concentration of paramagnetic impurities, and single electron spins show the longest room-temperature spin dephasing times ever observed in solid-state systems.
Abstract: As quantum mechanics ventures into the world of applications and engineering, materials science faces the necessity to design matter to quantum grade purity. For such materials, quantum effects define their physical behaviour and open completely new (quantum) perspectives for applications. Carbon-based materials are particularly good examples, highlighted by the fascinating quantum properties of, for example, nanotubes or graphene. Here, we demonstrate the synthesis and application of ultrapure isotopically controlled single-crystal chemical vapour deposition (CVD) diamond with a remarkably low concentration of paramagnetic impurities. The content of nuclear spins associated with the (13)C isotope was depleted to 0.3% and the concentration of other paramagnetic defects was measured to be <10(13) cm(-3). Being placed in such a spin-free lattice, single electron spins show the longest room-temperature spin dephasing times ever observed in solid-state systems (T2=1.8 ms). This benchmark will potentially allow observation of coherent coupling between spins separated by a few tens of nanometres, making it a versatile material for room-temperature quantum information processing devices. We also show that single electron spins in the same isotopically engineered CVD diamond can be used to detect external magnetic fields with a sensitivity reaching 4 nT Hz(-1/2) and subnanometre spatial resolution.
1,751 citations