We perform a proof-of-principle demonstration of the measurement-device-independent quantum key distribution protocol using weak coherent states and polarization-encoded qubits over two optical fiber links 8.5 km each. Each link was independently stabilized against polarization drifts full-polarization control system employing wavelength-multiplexed channels. A linear-optics-based Bell-state analyzer built into intermediate station, Charlie, which is connected to both Alice Bob via links....

We have experimentally demonstrated a decoy-state quantum key distribution scheme (QKD) with heralded single-photon source based on parametric down-conversion. used one-way Bennett-Brassard 1984 protocol four states and one-detector phase-coding scheme, which is immune to recently proposed time-shift attacks, photon-number splitting can also be proven secure against Trojan horse attacks any other standard individual or coherent attacks. In principle, the setup tolerate highest losses it give...

The secure transfer of information is an important problem in modern telecommunications. Quantum key distribution (QKD) provides a solution to this by using individual quantum systems generate correlated bits between remote parties, that can be used extract secret key. QKD with D-dimensional channels security advantages grow increasing D. However, the vast majority implementations has been restricted two dimensions. Here we demonstrate feasibility higher dimensions for real-world...

Multiplexing is a strategy to augment the transmission capacity of communication system. It consists combining multiple signals over same data channel and it has been very successful in classical communications. However, use enhanced channels only reached limited practicality quantum communications (QC) as requires manipulation systems higher dimensions. Considerable effort being made towards QC using high-dimensional encoded into transverse momentum single photons, but so far no approach...

Kochen-Specker (KS) sets are key tools for proving some fundamental results in quantum theory and also have potential applications information processing. However, so far, their intrinsic complexity has prevented experimentalists from using them any application. The KS set requiring the smallest number of contexts been recently found. Relying on this simple set, here we report an input state-independent experimental technique to certify whether a measurements is actually accessing...

A long-standing problem in quantum mechanics is the minimum number of observables required for characterization unknown pure states. The solution to this especially important developing field high-dimensional information processing. In work we demonstrate that any d-dimensional state unambiguously reconstructed by measuring five observables, is, via projective measurements onto states orthonormal bases. Thus, our method total different measurement outcomes (5d) scales linearly with d....

Abstract The optical fibre is an essential tool for our communication infrastructure since it the main transmission channel communications. latest major advance in technology space-division multiplexing, where new designs and components establish multiple co-existing data channels based on light propagation over distinct transverse modes. Simultaneously, there have been many recent developments field of quantum information processing, with novel protocols devices areas such as computing...

Multi-port beam splitters are cornerstone devices for high-dimensional quantum information tasks, which can outperform the two-dimensional ones. Nonetheless, fabrication of such has proven to be challenging with progress only recently achieved advent integrated photonics. Here, we report on production high-quality <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>N</mml:mi> <mml:mo>×</mml:mo> </mml:math> (with <mml:mo>=</mml:mo> <mml:mn>4</mml:mn>...

A real-time polarization control system employing two nonorthogonal reference signals multiplexed in either time or wavelength with the data signal is presented. It shown, theoretically and experimentally, that complete of multiple states can be attained controllers closed-loop configuration. Experimental results show negligible added penalties, corresponding to an average optical Quantum Bit Error Rate 0.044%, achieved response times smaller than 10 ms, without significant introduction...

Any practical realization of entanglement-based quantum communication must be intrinsically secure and able to span long distances avoiding the need a straight line between communicating parties. The violation Bell's inequality offers method for certification links without knowing inner workings devices. Energy-time entanglement satisfies all these requirements. However, currently there is fundamental obstacle with standard configuration adopted: an intrinsic geometrical loophole that can...

Quantum measurements on a two-level system can have more than two independent outcomes, and in this case, the measurement cannot be projective. Measurements of general type are essential to an operational approach quantum theory, but so far, nonprojective character only verified experimentally by already assuming specific model parts experimental setup. Here, we overcome restriction using device-independent approach. In experiment pairs polarization-entangled photonic qubits violate 8...

In this paper we demonstrate an active polarization drift compensation scheme for optical fibres employed in a quantum key distribution experiment with encoded qubits. The signals are wavelength multiplexed one fibre along two classical side channels that provide the control information scheme. This set-up allows us to continuously track any change without need interrupt exchange. results obtained show fast rotations of order 40π rad s−1 effectively compensated for. We our continuous even...

We experimentally demonstrate stable and user-adjustable single-photon interference in a 1 km long fiber- optical Mach-Zehnder interferometer, using an active phase control system with the feedback provided by classical laser. are able to continuously tune difference between interferometer arms modulator, which is synchronized gate window of detectors. The employs piezoelectric fiber stretcher stabilize drift interferometer. A net visibility 0.97 obtained, yielding future possibilities for...

By employing real-time monitoring of single-photon avalanche photodiodes we demonstrate how two types practical eavesdropping strategies, the after-gate and time-shift attacks, may be detected.Both attacks are identified with detectors operating without any special modifications, making this proposal well suited for real-world applications.The system is based on accumulating statistics times between consecutive detection events, extracting afterpulse overall efficiency in using mathematical...

We report on a new class of dimension witnesses, based quantum random access codes, which are function the recorded statistics and that have different bounds for all possible decompositions high-dimensional physical system. Thus, it certifies system has distinct feature identifying whether is decomposable in terms lower dimensional subsystems. To demonstrate practicability this technique, we used to experimentally certify generation an irreducible 1024-dimensional photonic state. Therefore,...

The secure transfer of information is critical for the ever-increasing demands digital world. Continuous-variable quantum key distribution (CV-QKD) a technology that can potentially provide information-theoretic security to cryptographic systems. CV-QKD highly attractive thanks high secret rate generation over metropolitan distances and integration with current classical communication networks. Here we demonstrate across 15 km multi-core fiber (MCF) where take advantage one core remotely...

For eight-dimensional quantum systems there is a Kochen-Specker (KS) set of 40 yes-no tests that related to the Greenberger-Horne-Zeilinger (GHZ) proof Bell's theorem. Here we experimentally implement this KS using an Hilbert space spanned by transverse momentum single photons. We show experimental results these violate state-independent noncontextuality inequality. In addition, that, if system prepared in states are formally equivalent three-qubit GHZ and W states, then subset 16 inequality...

Abstract The recent development of perovskite light emitting diodes (PeLEDs) has the potential to revolutionize fields optical communication and lighting devices, due their simplicity fabrication outstanding properties. Here we demonstrate that PeLEDs can also be used in field quantum technologies by implementing a highly-secure random number generator (QRNG). Modern QRNGs certify privacy are posed replace classical generators applications such as encryption gambling, therefore need cheap,...

Photonic spatial quantum states are a subject of great interest for applications in communication. One important challenge has been how to dynamically generate these using only fiber-optical components. Here we propose and experimentally demonstrate an all-fiber system that can switch between any general transverse qubit state based on linearly polarized modes. Our platform is fast optical Sagnac interferometer combined with photonic lantern few-mode fibers. We show switching times modes the...

In this paper, we analyze the impact of spontaneous Raman scattered noise generated from multiple optical classical channels on a single quantum key distribution channel, all within telecom C-band. We experimentally measure up to 14 continuous-wave laser sources with different wavelengths using dense wavelength division multiplexing (DWDM) standard, in both propagation directions respect QKD over standard SMF-28 fiber lengths. then simulate expected secure generation rate for...

Device-independent quantum communication will require a loophole-free violation of Bell inequalities. In typical scenarios where line sight between the communicating parties is not available, it convenient to use energy-time entangled photons due intrinsic robustness while propagating over optical fibers. Here we show an Clauser-Horne-Shimony-Holt inequality with two separated by 3.7 km deployed fiber network belonging University Concepción in Chile. Remarkably, this first spatially that...

Recently, a protocol for quantum state discrimination (QSD) in multiparty scenario has been introduced [Phys. Rev. Lett. 111, 100501 (2013)]. In this protocol, Alice generates system one of two predefined nonorthogonal qubit states, and the goal is to send generated information different parties without classical communication exchanged between them during protocol's session. The interesting feature that, by resorting sequential generalized measurements onto single system, there nonvanishing...

Time-bin (TB) and energy-time (ET) entanglements are crucial resources for long-distance quantum information processing. However, their standard implementations suffer from the so-called post-selection loophole that allows classical simulation thus prevents advantage. The has been addressed in proof-of-principle experiments. An open problem though is to close it real-life applications based on integrated technologies. This especially important since, so far, all sources of TB ET loophole....

Wave-particle duality is one of the most notable and counterintuitive features quantum mechanics, illustrating that two incompatible observables cannot be measured simultaneously with arbitrary precision. In this work, we experimentally demonstrate equivalence wave-particle entropic uncertainty relations using orbital angular momentum (OAM) states light. Our experiment uses an innovative reconfigurable platform composed few-mode optical fibers photonic lanterns, showcasing versatility...

We present a bright, narrowband, portable, quasi-phase-matched two-crystal source generating polarization-entangled photon pairs at 809 nm and 1555 maximum rate of 1.2 × 10 6 s -1 THz mW after coupling to single-mode fiber.The quantum channel the synchronization signal gating single detector are multiplexed in same optical fiber length 27 km by means wavelength division multiplexers (WDM) having 100 GHz (0.8 nm) spacing between channels.This implementation makes communication applications...