In a quantum computer, creating superpositions of bits (qubits) in different states can lead to speed-up over classical computers [1], but mechanics also allows for the superposition circuits [2]. fact, it has recently been theoretically predicted that superimposing circuits, each with gate order, could provide an even further computational advantage [3-5]. Here, we experimentally demonstrate this enhancement by applying two gates both possible orders determine whether commute or...

Investigating the role of causal order in quantum mechanics has recently revealed that distribution events may not be a-priori well-defined theory. While this triggered a growing interest on theoretical side, creating processes without is an experimental task. Here we report first decisive demonstration process with indefinite order. To do this, quantify how incompatible our set-up definite by measuring 'causal witness'. This mathematical object incorporates series measurements which are...

In this work, we study the transmission of classical information through three completely depolarizing channels in superposition different causal orders. We thus introduce quantum 3-switch as a resource for communications. perform new kind control that was not accessible to previously treated two-channel case. The fine and full achieved using selected combinations orders let us uncover features: non monotonous behavior on with respect number involved, values depending specific considered....

Abstract In standard quantum mechanics, complex numbers are used to describe the wavefunction. Although this has so far proven sufficient predict experimental results, there is no theoretical reason choose them over real or generalizations of numbers, that is, hyper-complex numbers. Experiments performed date have insufficient, but need for remains an open question. Here we experimentally probe theories, studying one their deviations from theory: non-commutativity phases. We do by passing...

Abstract We uncover new features on the study of a two-level atom interacting with one two cavities in coherent superposition. The Jaynes-Cummings model is used to describe atom–field interaction and effects quantum indefiniteness such an interaction. show that control undefined manner allows novel possibilities manipulate atomic dynamics demand which are not achievable conventional way. In addition, it shown creates highly entangled states cavity fields taking Bell-like or...

Harnessing the frequency dimension in integrated photonics offers key advantages terms of scalability, noise resilience, parallelization, and compatibility with telecom multiplexing techniques. Integrated ring resonators have been used to generate frequency-entangled states through spontaneous four-wave mixing. However, state-of-the-art are limited by trade-offs among size, spectral separation, efficient photon pair generation. We developed silicon a footprint below 0.05 mm2 providing more...

In quantum Shannon theory, transmission of information is enhanced by features. Up to very recently, the trajectories remained fully classical. Recently, a new paradigm was proposed playing tricks on two completely depolarizing channels i.e. using coherent control in space or time channels. We extend here this through network an arbitrary number $N$ with individual capacity preservation characteristics case indefinite causal order. propose formalism assess most general order scenario...

We study continuous-variable entanglement of bright quantum states in a pair evanescently coupled nonlinear ${\ensuremath{\chi}}^{(2)}$ waveguides operating the regime degenerate down conversion. consider case where only energy nonlinearly generated fields is exchanged between while pump stay independently guided each original waveguide. show that this device, when operated depletion regime, entangles two noninteracting modes due to cascade effect. It also shown two-color quadripartite can...

Multi-photon state generation is of great interest for near-future quantum simulation and computation experiments.To-date spontaneous parametric down-conversion still the most promising process, even though two major impediments exist: accidental photon noise (caused by probabilistic non-linear process) imperfect single-photon purity (arising from spectral entanglement between pairs).In this work, we overcome both these difficulties (1) exploiting a passive temporal multiplexing scheme (2)...

In his recent article [arXiv:1604.04950], Adler questions the usefulness of bound found in our experimental search for genuine effects hyper-complex quantum mechanics [arXiv:1602.01624]. Our experiment was performed using a black-box (instrumentalist) approach to generalized probabilistic theories; therefore, it does not assume priori any particular underlying mechanism. From that point view results do indeed place meaningful bounds on possible "post-quantum theories", including quaternionic...

Quantum Fisher information is the principal tool used to give ultimate precision bound on estimation of parameters for quantum channels. In this work, we present analytical expressions with three noisy channels case where are in superposition causal orders. We found that increases as number orders certain combinations. also show combinations attain higher bounds than others same Based our results, chose best probing schemes using indefinite structures

Views Icon Article contents Figures & tables Video Audio Supplementary Data Peer Review Share Twitter Facebook Reddit LinkedIn Tools Reprints and Permissions Cite Search Site Citation L. M. Procopio, O. Rosas‐Ortiz, V. Velázquez; Spatial correlation of photon pairs produced in spontaneous parametric down‐conversion. AIP Conf. Proc. 11 October 2010; 1287 (1): 80–84. https://doi.org/10.1063/1.3507428 Download citation file: Ris (Zotero) Reference Manager EasyBib Bookends Mendeley Papers...

In standard quantum mechanics, complex numbers are used to describe the wavefunction. Although have proven sufficient predict results of existing experiments, there is no apparent theoretical reason choose them over real or generalizations numbers, i.e. hyper-complex numbers. Experiments performed date that insufficient, but whether not required remains an open question. Quantum theories based on one example a post-quantum theory, which must be put firm experimental foundation. Here we...

Analytical expressions are derived for the distribution rates of spatial coincidences in counting photons produced by spontaneous parametric down conversion. Gaussian profiles assumed wave function idler and signal light created type‐I The describe ellipses on detection planes that oriented at different angles according to photon either horizontal–horizontal, vertical–vertical, horizontal–vertical, or vertical–horizontal position variables. predictions agreement with experimental data...

We study the quantum forces that act between two nearby conductors due to electronic tunnelling. derive an expression for these by calculating flux of momentum arising from overlap evanescent fields. Our result is written in terms reflection amplitudes and it has same structure as Lifshitz's formula electromagnetically mediated Casimir forces. evaluate tunnelling force semiinfinite thin films separated insulating gap. discuss some applications our results.

Modulation conditioned on measurements entangled photonic quantum states is a cornerstone technology of optical information processing. Performing this task with low latency requires combining single-photon-level detectors both electronic logic processing and modulation in close proximity. In the technologically relevant telecom wavelength band, detection best performed high-efficiency, low-noise, high-speed based photon-induced breakdown superconductivity. Therefore, using these devices for...

Accidental photon noise and imperfect single-photon purity in spontaneous parametric down-conversion (SPDC) at telecom wavelengths are overcome by exploiting a passive temporal multiplexing scheme optimizing the spectral properties of down- converted photons.

Harnessing the frequency dimension in integrated photonics offers key advantages terms of scalability, noise resilience, parallelization and compatibility with telecom multiplexing techniques. Integrated ring resonators have been used to generate frequency-entangled states through spontaneous four-wave-mixing. However, state-of-the-art are limited by trade-offs size, number modes spectral separation. We developed silicon a foot-print below 0.05 mm2 providing more than 70 channels separated...

We demonstrate for the first time a proof of concept frequency-domain fully-connected network using parallel measurements applied to frequency-entangled photon pairs from 21 GHz Silicon On Insulator (SOI) micro-resonator.

In this work, we uncover new features on the study of a two-level atom interacting with one two cavities in coherent superposition. The James-Cummings model is used to describe atom-field interaction and effects quantum indefiniteness such an interaction. We show that control undefined manner allows novel possibilities manipulate atomic dynamics demand which are not achievable conventional way. addition, it shown creates highly entangled states cavity fields taking Bell-like or...