Gaussian entanglement for quantum key distribution from a single-mode squeezing source

Eberle, T.; Händchen, Vitus; Duhme, Jörg; Franz, Titus; Furrer, Fabian; Schnabel, R.; Werner, R. F.

doi:10.1088/1367-2630/15/5/053049

Cited by 28 publications

(20 citation statements)

References 40 publications

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“…For instance, a purification ρ AE of ρ A is represented by the two mode squeezed vacuum state, |Ψ ξ = 1 cosh ξ n (tanh ξ) n |n A |n E , where ξ is a squeezing parameter. This state can be regarded as an optical approximate version of an EPR entangled state and it has been recently used in a CV-QKD scheme [28]. If Eve controls the system E, she can gain information on the quadrature outputs measured by Alice.…”

Section: Fig S1 Leftmentioning

confidence: 99%

Source-Device-Independent Ultrafast Quantum Random Number Generation

Marangon¹,

Vallone²,

Villoresi³

2017

Phys. Rev. Lett.

140

126

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Secure random numbers are a fundamental element of many applications in science, statistics, cryptography and more in general in security protocols. We present a method that enables the generation of high-speed unpredictable random numbers from the quadratures of an electromagnetic field without any assumption on the input state. The method allows to eliminate the numbers that can be predict due the presence of classical and quantum side information. In particular, we introduce a procedure to estimate a bound on the conditional min-entropy based on the Entropic Uncertainty Principle for position and momentum observables of infinite dimensional quantum systems. By the above method, we experimentally demonstrated the generation of secure true random bits at a rate greater than 1 Gbit/s.Introduction -Quantum Random Number Generators (QRNG) exploits intrinsic probabilistic quantum processes to generate true random numbers. Indeed, the expression "QRNG" was first introduced for a device based on the decay of radioactive nuclei [1]. Afterwards, QRNGs exploiting the versatility of light were realized: such devices are based on optical processes such as photon welcher weg [2][3][4], photon time of arrival [5][6][7] or vacuum quadratures [8][9][10][11].Usually, the assessment of the randomness of the generated numbers is obtained by applying statistical tests on the output bits. In most of the QRNGs, passing the tests is the only method used to certify the randomness. In case of failure (attributed to hardware problem since the process is assumed to be "random"), numbers are algorithmically post-processed until the tests are passed.However, this procedure con only certifies that the numbers are identically and independently distributed (i.i.d.) with respect to those [12] applied tests. Indeed, a posteriori statistical tests cannot certify that the numbers are not known to someone possessing side information about the generator. For instance, it is not possible to eliminate hardware noise, which is a source of classical side information for an eavesdropper, Eve, who may be able to control it. Hence, a statistical test a posteriori cannot establish whether the numbers are originated by the quantum process or by the noisy hardware. Moreover, even assuming a QRNG with an ideal noiseless hardware, a statistical test cannot reveal whether the outputs arise from a a quantum measurements and then are intrinsically random. For instance, a polarization welcher weg QRNG with an optical source emitting photons in a completely mixed polarization state can be seen as the photonic version of a fair coin. The random sequence can be predicted by Eve if she knows "the coin's equations of motion" (namely she has classical side information) or if she holds a quantum system correlated with the QRNG (namely she has quantum side information).The quantity that evaluates the amount of side information on a random sequence Z is the so called conditional quantum min-entropy H min (Z|E) [13]. However, such min-entropy is generally hard to estimate....

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Section: Fig S1 Leftmentioning

confidence: 99%

Source-Device-Independent Ultrafast Quantum Random Number Generation

Marangon¹,

Vallone²,

Villoresi³

2017

Phys. Rev. Lett.

140

126

View full text Add to dashboard Cite

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“…While the present proof-of-principle experiment demonstrates the viability of spatial multiplexing as applied to secret sharing, proving the security of this scheme is beyond the scope of this work. Security for two-mode squeezed vacuum states has previously been shown for two-party communication [15], and there have been experimental demonstrations of CV QKD using single [16] and two-mode squeezing sources [17]. A generic classical secret sharing protocol works as follows.…”

Section: Introductionmentioning

confidence: 99%

Multi-channel entanglement distribution using spatial multiplexing from four-wave mixing in atomic vapor

Gupta

Horrom

Anderson

et al. 2015

Journal of Modern Optics

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Four-wave mixing in atomic vapor allows for the generation of multi-spatial-mode states of light containing many pairs of two-mode entangled vacuum beams. This in principle can be used to send independent secure keys to multiple parties simultaneously using a single light source. In our experiment, we demonstrate this spatial multiplexing of information by selecting three independent pairs of entangled modes and performing continuous-variable measurements to verify the correlations between entangled partners. In this way, we generate three independent pairs of correlated random bit streams that could be used as secure keys. We then demonstrate a classical four-party secret sharing scheme as an example for how this spatially multiplexed source could be used.

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“…A more detailed description of the squeezedlight source, the homodyne measurement set-up and the locking scheme is given in ref. 20. Figure 4 presents the main result of this work.…”

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confidence: 96%

Observation of one-way Einstein–Podolsky–Rosen steering

et al. 2012

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The distinctive non-classical features of quantum physics were first discussed in the seminal paper 1 by A. Einstein, B. Podolsky and N. Rosen (EPR) in 1935. In his immediate response 2 , E. Schrödinger introduced the notion of entanglement, now seen as the essential resource in quantum information 3-5 as well as in quantum metrology [6][7][8] . Furthermore, he showed that at the core of the EPR argument is a phenomenon that he called steering. In contrast to entanglement and violations of Bell's inequalities, steering implies a direction between the parties involved. Recent theoretical works have precisely defined this property, but the question arose as to whether there are bipartite states showing steering only in one direction 9,10 . Here, we present an experimental realization of two entangled Gaussian modes of light that in fact shows the steering effect in one direction but not in the other. The generated one-way steering gives a new insight into quantum physics and may open a new field of applications in quantum information.The steering effect can be described by considering two remote observers, Alice and Bob, who share a bipartite quantum state. Their local systems are in a mixed state and therefore permit a decomposition into pure states. Schrödinger found that within quantum mechanics certain states do not allow such a decomposition locally. Depending on the observable Alice chooses to measure, Bob's local state is decomposed into incompatible mixtures of conditional states. So, if pure states were a local complete description of Bob's system, this would require some interaction from Alice to Bob. This is what Schrödinger named steering and Einstein later called the 'spooky action at a distance'. The first experimental demonstration of this effect was achieved by Ou et al.11 , and was followed by a great number of experiments [12][13][14][15] .Steering is strictly stronger than entanglement and strictly weaker than the violation of a Bell inequality; that is, steering does not imply the violation of any Bell inequality, while the violation of at least one Bell inequality immediately implies steering in both directions 16 , as shown in Fig. 1. In contrast to entanglement and Bell tests, Alice and Bob have certain roles in the steering scenario that are not interchangeable. This intrinsic asymmetry raises the question 9 of whether there are physical states certifying steering only in one direction for arbitrary observables. This one-way steering would lead to the peculiar situation that two experimenters measuring the same observables on their subsystems would describe the same shared state in qualitatively different ways. Whereas, in general, this question cannot as yet be answered, in the Gaussian regime (that is, for Gaussian state preparation and Gaussian measurements) the answer is yes. In a pioneering paper by H.-A. Bachor and co-workers, two-way steering with an asymmetry in the steering strengths was observed 17 . Their theoretical analysis proposes a possible extension of their set-up with a v...

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Gaussian entanglement for quantum key distribution from a single-mode squeezing source

Cited by 28 publications

References 40 publications

Source-Device-Independent Ultrafast Quantum Random Number Generation

Source-Device-Independent Ultrafast Quantum Random Number Generation

Multi-channel entanglement distribution using spatial multiplexing from four-wave mixing in atomic vapor

Observation of one-way Einstein–Podolsky–Rosen steering

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