The Experts below are selected from a list of 120027 Experts worldwide ranked by ideXlab platform
Radim Filip - One of the best experts on this subject based on the ideXlab platform.
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Experimental test of the strongly nonclassical character of a noisy squeezed single-Photon State
Physical Review A, 2012Co-Authors: Miroslav Jezek, Jaromír Fiurášek, Radim Filip, Ruifang Dong, Anders Tipsmark, Ladislav Mista, Ulrik L. AndersenAbstract:We experimentally verify the quantum non-Gaussian character of a conditionally generated noisy squeezed single-Photon State with a positive Wigner function. Employing an optimized witness based on probabilities of squeezed vacuum and squeezed single-Photon States, we prove that the State cannot be expressed as a mixture of Gaussian States. In our experiment, the non-Gaussian State is generated by conditional subtraction of a single Photon from a squeezed vacuum State. The State is probed with a homodyne detector and the witness is determined by averaging a suitable pattern function over the measured homodyne data. Our experimental results are in good agreement with a theoretical fit obtained from a simple yet realistic model of the experimental setup.
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Unconditional conversion between a single-Photon State and a coherent-State superposition via squeezing operation
Conference on Lasers and Electro-Optics 2012, 2012Co-Authors: Yoshichika Miwa, Radim Filip, Jun-ichi Yoshikawa, Noriaki Iwata, Mamoru Endo, Petr Marek, Peter Van Loock, Akira FurusawaAbstract:We experimentally demonstrate a conversion of a single-Photon State into a superposition of two weak coherent States and its inverse, via squeezing operation based on offline-prepared squeezed States, measurement and feedforward.
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Experimental test of quantum non-Gaussianity of heralded single Photon State
Physical review letters, 2011Co-Authors: Miroslav Jezek, Ivo Straka, Michal Mičuda, Miloslav Dušek, Jaromír Fiurášek, Radim FilipAbstract:We report on experimental verification of quantum non-Gaussianity of a heralded single Photon State with positive Wigner function. We unambiguously demonstrate that the generated State cannot be expressed as a mixture of Gaussian States. A sufficient information to witness the quantum non-Gaussianity is obtained from a standard Photon anti-correlation measurement.
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detecting quantum States with a positive wigner function beyond mixtures of gaussian States
Physical Review Letters, 2011Co-Authors: Radim Filip, Ladislav MistaAbstract:We propose a criterion giving a sufficient condition for quantum States of a harmonic oscillator not to be expressible as a convex mixture of Gaussian States. This nontrivial property is inherent to, e.g., a single-Photon State and the criterion thus allows one to reveal a signature of the State even in quantum States with a positive Wigner function. The criterion relies on directly measurable Photon number probabilities and enables detection of this manifestation of a single-Photon State in quantum States produced by solid-State single-Photon sources in a weak coupling regime.
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Continuous-variable teleportation of a negative Wigner function
Physical Review A, 2010Co-Authors: Ladislav Mista, Radim Filip, Akira FurusawaAbstract:Teleportation is a basic primitive for quantum communication and quantum computing. We address the problem of continuous-variable (unconditional and conditional) teleportation of a pure single-Photon State and a mixed attenuated single-Photon State generally in a nonunity-gain regime. Our figure of merit is the maximum negativity of the Wigner function, which demonstrates a highly nonclassical feature of the teleported State. We find that the negativity of the Wigner function of the single-Photon State can be unconditionally teleported for an arbitrarily weak squeezed State used to create the entangled State shared in teleportation. In contrast, for the attenuated single-Photon State there is a strict threshold squeezing one has to surpass to successfully teleport the negativity of its Wigner function. The conditional teleportation allows one to approach perfect transmission of the single Photon for an arbitrarily low squeezing at a cost of decrease of the success rate. In contrast, for the attenuated single Photon State, conditional teleportation cannot overcome the squeezing threshold of the unconditional teleportation and it approaches negativity of the input State only if the squeezing increases simultaneously. However, as soon as the threshold squeezing is surpassed, conditional teleportation still pronouncedly outperforms the unconditional one. The main consequences for quantum communication and quantum computing with continuous variables are discussed.
Ladislav Mista - One of the best experts on this subject based on the ideXlab platform.
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Experimental test of the strongly nonclassical character of a noisy squeezed single-Photon State
Physical Review A, 2012Co-Authors: Miroslav Jezek, Jaromír Fiurášek, Radim Filip, Ruifang Dong, Anders Tipsmark, Ladislav Mista, Ulrik L. AndersenAbstract:We experimentally verify the quantum non-Gaussian character of a conditionally generated noisy squeezed single-Photon State with a positive Wigner function. Employing an optimized witness based on probabilities of squeezed vacuum and squeezed single-Photon States, we prove that the State cannot be expressed as a mixture of Gaussian States. In our experiment, the non-Gaussian State is generated by conditional subtraction of a single Photon from a squeezed vacuum State. The State is probed with a homodyne detector and the witness is determined by averaging a suitable pattern function over the measured homodyne data. Our experimental results are in good agreement with a theoretical fit obtained from a simple yet realistic model of the experimental setup.
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detecting quantum States with a positive wigner function beyond mixtures of gaussian States
Physical Review Letters, 2011Co-Authors: Radim Filip, Ladislav MistaAbstract:We propose a criterion giving a sufficient condition for quantum States of a harmonic oscillator not to be expressible as a convex mixture of Gaussian States. This nontrivial property is inherent to, e.g., a single-Photon State and the criterion thus allows one to reveal a signature of the State even in quantum States with a positive Wigner function. The criterion relies on directly measurable Photon number probabilities and enables detection of this manifestation of a single-Photon State in quantum States produced by solid-State single-Photon sources in a weak coupling regime.
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Continuous-variable teleportation of a negative Wigner function
Physical Review A, 2010Co-Authors: Ladislav Mista, Radim Filip, Akira FurusawaAbstract:Teleportation is a basic primitive for quantum communication and quantum computing. We address the problem of continuous-variable (unconditional and conditional) teleportation of a pure single-Photon State and a mixed attenuated single-Photon State generally in a nonunity-gain regime. Our figure of merit is the maximum negativity of the Wigner function, which demonstrates a highly nonclassical feature of the teleported State. We find that the negativity of the Wigner function of the single-Photon State can be unconditionally teleported for an arbitrarily weak squeezed State used to create the entangled State shared in teleportation. In contrast, for the attenuated single-Photon State there is a strict threshold squeezing one has to surpass to successfully teleport the negativity of its Wigner function. The conditional teleportation allows one to approach perfect transmission of the single Photon for an arbitrarily low squeezing at a cost of decrease of the success rate. In contrast, for the attenuated single Photon State, conditional teleportation cannot overcome the squeezing threshold of the unconditional teleportation and it approaches negativity of the input State only if the squeezing increases simultaneously. However, as soon as the threshold squeezing is surpassed, conditional teleportation still pronouncedly outperforms the unconditional one. The main consequences for quantum communication and quantum computing with continuous variables are discussed.
Guang-can Guo - One of the best experts on this subject based on the ideXlab platform.
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Observation of nonlocal quantum interference between the origins of a four-Photon State in a silicon chip.
arXiv: Quantum Physics, 2021Co-Authors: Lan-tian Feng, Guang-can Guo, Ming Zhang, Di Liu, Yu-jie Cheng, Guo-ping Guo, Daoxin Dai, Mario Krenn, Xi-feng RenAbstract:Quantum mechanically, multiple particles can jointly be in a coherent superposition of two or more different States at the same time. This property is called quantum entanglement, and gives rise to characteristic nonlocal interference and stays at the heart of quantum information process. Here, rather than interference of different intrinsic properties of particles, we experimentally demonstrated coherent superposition of two different birthplaces of a four-Photon State. The quantum State is created in four probabilistic Photon-pair sources, two combinations of which can create Photon quadruplets. Coherent elimination and revival of distributed 4-Photons can be fully controlled by tuning a phase. The stringent coherence requirements are met by using a silicon-based integrated Photonic chip that contains four spiral waveguides for producing Photon pairs via spontaneous four-wave mixing. The experiment gives rise to peculiar nonlocal phenomena without any obvious involvement of entanglement. Besides several potential applications that exploit the new on-chip technology, it opens up the possibility for fundamental studies on nonlocality with spatially separated locations.
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Entanglement and interference between different degrees of freedom of Photon States
Physical Review A, 2007Co-Authors: Fang-wen Sun, Bingxuan Liu, Y. Huang, Yong-sheng Zhang, Guang-can GuoAbstract:In this paper, Photonic entanglement and interference are described and analyzed with the language of quantum information processing. Correspondingly, a Photon State involving several degrees of freedom is represented in an expression based on the permutation symmetry of bosons. In this expression, each degree of freedom of a single Photon is regarded as a qubit and operations on Photons as qubit gates. The two-Photon Hong-Ou-Mandel interference is well interpreted with it. Moreover, the analysis reveals the entanglement between different degrees of freedom in a four-Photon State from parametric down conversion, even if there is no entanglement between them in the two-Photon State. The entanglement will decrease the State purity and Photon interference visibility in the experiments on a four-Photon polarization State.
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Demonstration of Controllable Temporal Distinguishability in a Three-Photon State
Europhysics Letters (EPL), 2007Co-Authors: Bi-heng Liu, Fang-wen Sun, Y. X. Gong, Yun-feng Huang, Guang-can GuoAbstract:Multi-Photon interference is at the heart of the recently proposed linear optical quantum computing scheme and plays an essential role in many protocols in quantum information. Indistinguishability is what leads to the effect of quantum interference. Optical interferometers such as Michaelson interferometer provide a measure for second-order coherence at one-Photon level and Hong-Ou-Mandel interferometer was widely employed to describe two-Photon entanglement and indistinguishability. However, there is not an effective way for a system of more than two Photons. Recently, a new interferometric scheme was proposed to quantify the degree of multi-Photon distinguishability. Here we report an experiment to implement the scheme for three-Photon case. We are able to generate three Photons with different degrees of temporal distinguishability and demonstrate how to characterize them by the visibility of three-Photon interference. This method of quantitative description of multi-Photon indistinguishability will have practical implications in the implementation of quantum information protocols.
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Demonstration of temporal distinguishability in a four-Photon State and a six-Photon State.
Physical review letters, 2006Co-Authors: Guo-yong Xiang, Yuanyuan Huang, Fang-wen Sun, Pei Zhang, Guang-can GuoAbstract:An experiment is performed to demonstrate the temporal distinguishability of a four-Photon State and a six-Photon State, both from parametric down-conversion. The experiment is based on a multiPhoton interference scheme in a recently discovered projection measurement of a maximally entangled N-Photon State. By measuring the visibility of the interference dip, we can distinguish the various scenarios in the temporal distribution of the pairs and, thus, quantitatively determine the degree of temporal distinguishability of a multiPhoton State.
Masahito Ueda - One of the best experts on this subject based on the ideXlab platform.
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Tailor-made few-Photon State generation from squeezed atoms
1998Co-Authors: Hiroki Saito, Masahito UedaAbstract:This paper develops a method of manipulating the squeezed atom State to generate a few-Photon State whose phase or Photon-number fluctuations are prescribed at our disposal. The squeezed atom State is a collective atomic State whose quantum fluctuations in population difference or collective dipole are smaller than those of the coherent atom State. It is shown that the squeezed atom State can be generated by the interaction of atoms with a coherent State of the electromagnetic field, and that it can be used as a tunable source of squeezed radiation. A variety of squeezed States, including the Photon-number squeezed State and the phase squeezed State, can be produced by manipulating the atomic State. This is owing to the fact that quantum-statistical information of the atomic State is faithfully transferred to that of the Photon State. Possible experimental situations to implement our theory are discussed.
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Quantum-Controlled Few-Photon State Generated by Squeezed Atoms
Physical Review Letters, 1997Co-Authors: Hiroki Saito, Masahito UedaAbstract:General principles and experimental schemes for generating a desired few-Photon State from an aggregate of squeezed atoms are presented. Quantum-statistical information of the collective atomic dipole is found to be faithfully transferred to the Photon State even in a few-Photon regime. The controllability of few-Photon States is shown to increase with increasing the number of squeezed atoms.
Ulrik L. Andersen - One of the best experts on this subject based on the ideXlab platform.
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Experimental test of the strongly nonclassical character of a noisy squeezed single-Photon State
Physical Review A, 2012Co-Authors: Miroslav Jezek, Jaromír Fiurášek, Radim Filip, Ruifang Dong, Anders Tipsmark, Ladislav Mista, Ulrik L. AndersenAbstract:We experimentally verify the quantum non-Gaussian character of a conditionally generated noisy squeezed single-Photon State with a positive Wigner function. Employing an optimized witness based on probabilities of squeezed vacuum and squeezed single-Photon States, we prove that the State cannot be expressed as a mixture of Gaussian States. In our experiment, the non-Gaussian State is generated by conditional subtraction of a single Photon from a squeezed vacuum State. The State is probed with a homodyne detector and the witness is determined by averaging a suitable pattern function over the measured homodyne data. Our experimental results are in good agreement with a theoretical fit obtained from a simple yet realistic model of the experimental setup.