Shor's algorithm can find prime factors of a large number more efficiently than any known classical algorithm. Understanding the properties that gives the speedup is essential for a general and scalable construction. Here we present a realization of Shor's algorithm, that does not need any of the simplifications presently needed in current experiments and also gives smaller systematic errors than any former experimental implementation. Our realization is based on classical pass-transistor logic, runs at room temperature, and uses the same amount of resources as a scalable quantum computer. In this paper, the focus is not on the result of the factorization, but to compare our realization with current state-of-the-art experiment, factoring 15. Our result gives further insight to the resources needed for quantum computation, aiming for a true understanding of the subject.
We report the realization of a solid-state triggered single-photon source with narrow emission in the near infrared at room temperature. It is based on the photoluminescence of a single nickel-nitrogen NE8 colour centre in a chemical vapour deposited diamond nanocrystal. Stable single-photon emission has been observed in the photoluminescence under both continuous-wave and pulsed excitations. The realization of this source represents a step forward in the application of diamond-based single-photon sources to Quantum Key Distribution (QKD) under practical operating conditions.
We report experimental generation of non-classically correlated photon pairs from collective emission in a room-temperature atomic vapor cell. The nonclassical feature of the emission is demonstrated by observing a violation of the Cauchy-Schwarz inequality. Each pair of correlated photons are separated by a controllable time delay up to 2 microseconds. This experiment demonstrates an important step towards the realization of the Duan-Lukin-Cirac-Zoller scheme for scalable long-distance quantum communication.
The realization of a scalable quantum information processor has emerged over the past decade as one of the central challenges at the interface of fundamental science and engineering. Much progress has been made towards this goal. Indeed, quantum operations have been demonstrated on several trapped ion qubits, and other solid-state systems are approaching similar levels of control. Extending these techniques to achieve fault-tolerant operations in larger systems with more qubits remains an extremely challenging goal, in part, due to the substantial technical complexity of current implementation…
We report on the realization of a stable solid state room temperature source for single photons. It is based on the fluorescence of a single nitrogen-vacancy (NV) color center in a diamond nanocrystal. Antibunching has been observed in the fluorescence light under both continuous and pulsed excitation. Our source delivers 2*10^4 single-photon pulses per second at an excitation repetition rate of 10 MHz. The number of two-photon pulses is reduced by a factor of five compared to strongly attenuated coherent sources.
Experiments have reported the entanglement of two spatially separated macroscopic atomic ensembles at room temperature (Krauter et al 2011 Phys. Rev. Lett. 107 080503; Julsgaard et al 2001 Nature 413 400). We show how an Einstein-Podolsky-Rosen (EPR) paradox is realizable with this experiment. Our proposed test involves violation of an inferred Heisenberg uncertainty principle, which is a sufficient condition for an EPR paradox. This is a stronger test of nonlocality than entanglement. Our proposal would enable the first definitive confirmation of quantum EPR paradox correlations between two m…
In this paper, we present the experimental realization of multi-qubit gates $% Λ_n(not) $ in macroscopic ensemble of three-qubit and four-qubit molecules. Instead of depending heavily on the two-bit universal gate, which served as the basic quantum operation in quantum computing, we use pulses of well-defined frequency and length that simultaneously apply to all qubits in a quantum register. It appears that this method is experimentally convenient when this procedure is extended to more qubits on some quantum computation, and it can also be used in other physical systems.
We have trapped rubidium atoms in the magnetic field produced by a superconducting atom chip operated at liquid Helium temperatures. Up to $8.2\cdot 10^5$ atoms are held in a Ioffe-Pritchard trap at a distance of 440 $μ$m from the chip surface, with a temperature of 40 $μ$K. The trap lifetime reaches 115 s at low atomic densities. These results open the way to the exploration of atom--surface interactions and coherent atomic transport in a superconducting environment, whose properties are radically different from normal metals at room temperature.
The study of advanced quantum devices for energy storage has attracted the attention of the scientific community in the past few years. Although several theoretical progresses have been achieved recently, experimental proposals of platforms operating as quantum batteries under ambient conditions are still lacking. In this context, this work presents a feasible realization of a quantum battery in a carboxylate-based metal complex, which can store a finite amount of extractable work under the form of quantum discord at room temperature, and recharge by thermalization with a reservoir. Moreover, …
Recent progress in nonlinear optical materials and microresonators has brought quantum computing with bulk optical nonlinearities into the realm of possibility. This platform is of great interest, not only because photonics is an obvious choice for quantum networks, but also because it may be the only feasible route to quantum information processing at room temperature. We introduce a paradigm for room-temperature photonic quantum logic that significantly simplifies the realization of various quantum circuits, and in particular, of error correction. It uses only the strongest available bulk no…
A quantum model of Bose-Einstein condensation based on processes involving polaritons excited in an intracavity absorbing cell with resonance atoms, which is manifested in the spectral characteristics of the system, is considered. It is shown that the spectral 'condensation' appears which is directly related to the degeneracy of a weakly interacting gas of polaritons resulting in quasi-condensation at room temperature. The possibility of obtaining polariton condensation as a new phase state by using the confinement of polaritons in an atomic optical harmonic trap is discussed.
The lifetime of trapped ion ensembles corresponds to a crucial parameter determining the potential scalability of their prospective applications and is often limited by the achievable vacuum level in the apparatus. We report on the realization of a room-temperature $^{40}{\rm Ca}^{+}$ ion trapping vacuum apparatus with unprecedentedly low reaction rates of ions with a dominant vacuum contaminant: hydrogen. We present our trap assembly procedures and hydrogen pressure characterization by analysis of the CaH$^+$ molecule formation rate.
We report the first use of "logical labeling" to perform a quantum computation with a room-temperature bulk system. This method entails the selection of a subsystem which behaves as if it were at zero temperature - except for a decrease in signal strength - conditioned upon the state of the remaining system. No averaging over differently prepared molecules is required. In order to test this concept, we execute a quantum search algorithm in a subspace of two nuclear spins, labeled by a third spin, using solution nuclear magnetic resonance (NMR), and employing a novel choice of reference frame t…
Optically addressable spins associated with defects in wide-bandgap semiconductors are versatile platforms for quantum information processing and nanoscale sensing, where spin-dependent inter-system crossing (ISC) transitions facilitate optical spin initialization and readout. Recently, the van der Waals material hexagonal boron nitride (h-BN) has emerged as a robust host for quantum emitters (QEs), but spin-related effects have yet to be observed. Here, we report room-temperature observations of strongly anisotropic photoluminescence (PL) patterns as a function of applied magnetic field for s…
Efficient realization of quantum algorithms is among main challenges on the way towards practical quantum computing. Various libraries and frameworks for quantum software engineering have been developed. Here we present a software package containing implementations of various quantum gates and well-known quantum algorithms using PennyLane library. Additoinally, we used a simplified technique for decomposition of algorithms into a set of gates which are native for trapped-ion quantum processor and realized this technique using PennyLane library. The decomposition is used to analyze resources re…
Quantum computers are able to outperform classical algorithms. This was long recognized by the visionary Richard Feynman who pointed out in the 1980s that quantum mechanical problems were better solved with quantum machines. It was only in 1994 that Peter Shor came up with an algorithm that is able to calculate the prime factors of a large number vastly more efficiently than known possible with a classical computer. This paradigmatic algorithm stimulated the flourishing research in quantum information processing and the quest for an actual implementation of a quantum computer. Over the last fi…
We report room temperature operation of telecom wavelength single-photon detectors for high bit rate quantum key distribution (QKD). Room temperature operation is achieved using InGaAs avalanche photodiodes integrated with electronics based on the self-differencing technique that increases avalanche discrimination sensitivity. Despite using room temperature detectors, we demonstrate QKD with record secure bit rates over a range of fiber lengths (e.g. 1.26 Mbit/s over 50 km). Furthermore, our results indicate that operating the detectors at room temperature increases the secure bit rate for sho…
Very recently, Monz, et al. [arXiv:1507.08852] have reported the demonstration of factoring 15 using a scalable Shor algorithm with an ion-trap quantum computer. In this note, we remark that the report is somewhat misleading because there are three flaws in the proposed circuit diagram of Shor algorithm. We also remark that the principles behind the demonstration have not been explained properly, including its correctness and complexity.
The growing field of quantum computing is based on the concept of a q-bit which is a delicate superposition of 0 and 1, requiring cryogenic temperatures for its physical realization along with challenging coherent coupling techniques for entangling them. By contrast, a probabilistic bit or a p-bit is a robust classical entity that fluctuates between 0 and 1, and can be implemented at room temperature using present-day technology. Here, we show that a probabilistic coprocessor built out of room temperature p-bits can be used to accelerate simulations of a special class of quantum many-body syst…
Realization of practical terahertz wireless communications still faces many challenges. The receiver with high sensitivity is important for THz wireless communications. Here we demonstrate a terahertz receiver based on the cesium Rydberg atoms in a room-temperature vapor cell. The minimum detectable THz electric field is calibrated. With this receiver, the phase-sensitive conversion of amplitude-modulated or frequency-modulated terahertz waves into optical signals is performed. The results show that the atomic receiver has many advantages due to its quantum properties. Especially, the long dis…
Realization of devices based on quantum laws might lead to building processors that outperform their classical analogues and establishing unconditionally secure communication protocols. Solids do usually present a serious challenge to quantum coherence. However, owing to their spin-free lattice and low spin orbit coupling, carbon materials and particularly diamond are suitable for hosting robust solid state quantum registers. We show that scalable quantum logic elements can be realized by exploring long range magnetic dipolar coupling between individually addressable single electron spins asso…
The number of steps any classical computer requires in order to find the prime factors of an $l$-digit integer $N$ increases exponentially with $l$, at least using algorithms known at present. Factoring large integers is therefore conjectured to be intractable classically, an observation underlying the security of widely used cryptographic codes. Quantum computers, however, could factor integers in only polynomial time, using Shor's quantum factoring algorithm. Although important for the study of quantum computers, experimental demonstration of this algorithm has proved elusive. Here we report…
Lasers have revolutionized optical science and technology, but their microwave counterpart, maser, has not realized its great potential due to its demanding work conditions (high-vacuum for gas maser and liquid-helium temperature for solid-state maser). Room-temperature solid-state maser is highly desirable, but under such conditions the lifetimes of emitters (usually electron spins) are usually too short (~ns) for population inversion. The only room-temperature solid-state maser is based on a pentacene-doped p-terphenyl crystal, which has long spin lifetime (~0.1 ms). This maser, however, ope…
Intermodal quantum key distribution over an 18 km free-space channel with adaptive optics and room-temperature detectors
Università degli Studi di Padova（帕多瓦大学）；ThinkQuantum s.r.l.（思量子有限公司）；Institute of Photonics and Nanotechnology, National Council of Research of Italy（意大利国家研究委员会光子与纳米技术研究所）
Establishing quantum entanglement between individual nodes is crucial for building large-scale quantum networks, enabling secure quantum communication, distributed quantum computing, enhanced quantum metrology and fundamental tests of quantum mechanics. However, the shared entanglements have been merely observed in either extremely low-temperature or well-isolated systems, which limits the quantum networks for the real-life applications. Here, we report the realization of heralding quantum entanglement between two atomic ensembles at room temperature, where each of them contains billions of mo…
Dynamic Nuclear Polarization (DNP) is a powerful suite of techniques that deliver multifold signal enhancements in NMR and MRI. The generated athermal spin states can also be exploited for quantum sensing and as probes for many-body physics. Typical DNP methods require use of cryogens, large magnetic fields, and high power microwaves, which are expensive and unwieldy. Nanodiamond particles, rich in Nitrogen-Vacancy (NV) centers, have attracted attention as alternative DNP agents because they can potentially be optically hyperpolarized at room temperature. Indeed the realization of a miniature …
Recently room temperature superconductivity with Tc=15 degrees Celsius has been discovered in a pressurized complex ternary hydride, CSHx, which is a carbon doped H3S alloy. The nanoscale structure of H3S is a particular realization of the 1993 patent claim of superlattice of quantum wires for room temperature superconductors where the maximum Tc occurs at the top of a superconducting dome. Here we focus on the electronic structure of materials showing nanoscale heterostructures at atomic limit made of a superlattice of quantum wires like hole doped cuprate perovskites, organics, A15 intermeta…
Quantum coherent light-matter interactions have been at the forefront of scientific interest since the fundamental predictions of Einstein and the later work of Rabi. Direct observation of quantum coherent interactions entails probing the electronic wavefunction which requires that the electronic state of the matter does not de-phase during the measurement, a condition that can be satisfied by lengthening the coherence time or by shortening the observation time. The short de-phasing time in semiconductors has dictated that all coherent effects reported to date have been recorded directly only …
The discovery of van der Waals (vdW) magnets opened up a new paradigm for condensed matter physics and spintronic technologies. However, the operations of active spintronic devices with vdW magnets are so far limited to cryogenic temperatures, inhibiting its broader practical applications. Here, for the first time, we demonstrate room temperature spin-valve devices using vdW itinerant ferromagnet Fe5GeTe2 in heterostructures with graphene. The tunnel spin polarization of the Fe5GeTe2/graphene vdW interface is detected to be significantly large ~ 45 % and negative at room temperature. Lateral s…
We report the realization of a device based on a single Nitrogen-vacancy (NV) center in diamond coupled to a fiber-cavity for use as single photon source (SPS). The device consists of two concave mirrors each directly fabricated on the facets of two optical fibers and a preselected nanodiamond containing a single NV center deposited onto one of these mirrors. Both, cavity in- and output are directly fiber-coupled and the emission wavelength is easily tunable by variation of the separation of the two mirrors with a piezo-electric crystal. By coupling to the cavity we achieve an increase of the …
Strongly-correlated quantum many-body systems exhibits a variety of exotic phases with long-range quantum correlations, such as spin liquids and supersolids. Despite the rapid increase in computational power of modern computers, the numerical simulation of these complex systems becomes intractable even for a few dozens of particles. Feynman's idea of quantum simulators offers an innovative way to bypass this computational barrier. However, the proposed realizations of such devices either require very low temperatures (ultracold gases in optical lattices, trapped ions, superconducting devices) …
Room temperature Purcell enhanced single erbium ions in silicon-carbide-on-insulator microring resonators
RMIT University（皇家墨尔本理工大学）；National Institutes for Quantum Science and Technology（国立量子科学技术研究院）；The University of Melbourne（墨尔本大学）；Carnegie Mellon University（卡内基梅隆大学）
Single-photon emitters are essential for enabling several emerging applications in quantum information technology, quantum sensing and quantum communication. Scalable photonic platforms capable of hosting intrinsic or directly embedded sources of single-photon emission are of particular interest for the realization of integrated quantum photonic circuits. Here, we report on the first-time observation of room-temperature single-photon emitters in silicon nitride (SiN) films grown on silicon dioxide substrates. As SiN has recently emerged as one of the most promising materials for integrated qua…
We present and analyze a gated single photon avalanche detector using a sine gating scheme with a simple but effective low-pass filtering technique for fast low-noise single photon detection at telecom wavelength. The detector is characterized by 130 ps short gates applied with a frequency of 1.25 GHz, yields only 70 ps timing jitter and noise probabilities as low as 7E-7 per gate at 10% detection efficiency. We show that the detector is suitable for high rate quantum key distribution (QKD) and even at room temperature it could allow for QKD over distances larger than 25 km.
A d-orbital electron has an anisotropic electron orbital and is a source of magnetism. The realization of a 2-dimensional electron gas (2DEG) embedded at a LaAlO3/SrTiO3 interface surprised researchers in materials and physical sciences because the 2DEG consists of 3d-electrons of Ti with extraordinarily large carrier mobility, even in the insulating oxide heterostructure. To date, a wide variety of physical phenomena, such as ferromagnetism and the quantum Hall effect, have been discovered in this 2DEG systems, demonstrating the ability of the d-electron 2DEG systems to provide a material pla…
