scholarly journals Attainability of the quantum information bound in pure-state models

2017 ◽  
Vol 95 (4) ◽  
Author(s):  
Fabricio Toscano ◽  
Wellison P. Bastos ◽  
Ruynet L. de Matos Filho
Keyword(s):  
Quantum Information ◽  
Pure State ◽  
Information Bound ◽  
State Models

Probabilistic secret sharing through noise quantum channe

2012 ◽  
Vol 12 (3&4) ◽  
pp. 253-261
Author(s):  
Satyabrata Adhikari ◽  
Indranil Chakrabarty ◽  
Pankaj Agrawal
Keyword(s):  
Quantum Information ◽  
Secret Sharing ◽  
Mixed State ◽  
Pure State ◽  
Noisy Channel ◽  
Noisy Channels ◽  
Superdense Coding ◽  
Classical Information ◽  
Phase Damping ◽  
Realistic Situation

In a realistic situation, the secret sharing of classical or quantum information will involve the transmission of this information through noisy channels. We consider a three qubit pure state. This state becomes a mixed-state when the qubits are distributed over noisy channels. We focus on a specific noisy channel, the phase-damping channel. We propose a protocol for secret sharing of classical information with this and related noisy channels. This protocol can also be thought of as cooperative superdense coding. We also discuss other noisy channels to examine the possibility of secret sharing of classical information.

scholarly journals Quantum information bound on the energy

2019 ◽  
Vol 100 (12) ◽  
Author(s):  
Raphael Bousso ◽  
Arvin Shahbazi-Moghaddam ◽  
Marija Tomašević
Keyword(s):  
Quantum Information ◽  
Information Bound

Quantum Fisher metric and estimation for pure state models

1995 ◽  
Vol 201 (2-3) ◽  
pp. 119-124 ◽  
Author(s):  
Akio Fujiwara ◽  
Hiroshi Nagaoka
Keyword(s):  
Pure State ◽  
Fisher Metric ◽  
State Models

scholarly journals Measurability of D-concurrence

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
N. Karimi ◽  
A. Heshmati ◽  
M. Yahyavi ◽  
M. A. Jafarizadeh ◽  
A. Mohammadzadeh
Keyword(s):  
Quantum Information ◽  
Experimental Determination ◽  
Pure State ◽  
Information Science ◽  
Direct Method ◽  
Entanglement Measure ◽  
Quantum Information Science ◽  
The Subject ◽  
A Direct Method

AbstractAn effective approach to quantify entanglement of any bipartite systems is D-concurrence, which is important in quantum information science. In this paper, we present a direct method for experimental determination of the D-concurrence of an arbitrary bipartite pure state. To do this, we show that measurement of the D-concurrence of bipartite pure state can be conversed into the measurement performed on some observables so called generalized Gell-Mann operators. We first introduce the concept of D-concurrence for a bipartite system. Then we explain the method of measuring this entanglement measure for the pure state. Finally, for clarify of the subject, we give an example consisting of two parties A and B with dimensions 3.

Quantum Fisher Metric and Estimation for Pure State Models

2005 ◽  
pp. 220-228
Author(s):  
Akio Fujiwara ◽  
Hiroshi Nagaoka
Keyword(s):  
Pure State ◽  
Fisher Metric ◽  
State Models

scholarly journals 648 Hilbert-space dimensionality in a biphoton frequency comb: entanglement of formation and Schmidt mode decomposition

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Kai-Chi Chang ◽  
Xiang Cheng ◽  
Murat Can Sarihan ◽  
Abhinav Kumar Vinod ◽  
Yoo Seung Lee ◽  
...  
Keyword(s):  
Hilbert Space ◽  
Information Processing ◽  
Quantum Information ◽  
Pure State ◽  
Quantum Information Processing ◽  
Frequency Comb ◽  
High Dimensional ◽  
Time Frequency ◽  
Variable Time ◽  
Entanglement Of Formation

AbstractQudit entanglement is an indispensable resource for quantum information processing since increasing dimensionality provides a pathway to higher capacity and increased noise resilience in quantum communications, and cluster-state quantum computations. In continuous-variable time–frequency entanglement, encoding multiple qubits per photon is only limited by the frequency correlation bandwidth and detection timing jitter. Here, we focus on the discrete-variable time–frequency entanglement in a biphoton frequency comb (BFC), generating by filtering the signal and idler outputs with a fiber Fabry–Pérot cavity with 45.32 GHz free-spectral range (FSR) and 1.56 GHz full-width-at-half-maximum (FWHM) from a continuous-wave (cw)-pumped type-II spontaneous parametric downconverter (SPDC). We generate a BFC whose time-binned/frequency-binned Hilbert space dimensionality is at least 324, based on the assumption of a pure state. Such BFC’s dimensionality doubles up to 648, after combining with its post-selected polarization entanglement, indicating a potential 6.28 bits/photon classical-information capacity. The BFC exhibits recurring Hong–Ou–Mandel (HOM) dips over 61 time bins with a maximum visibility of 98.4% without correction for accidental coincidences. In a post-selected measurement, it violates the Clauser–Horne–Shimony–Holt (CHSH) inequality for polarization entanglement by up to 18.5 standard deviations with an S-parameter of up to 2.771. It has Franson interference recurrences in 16 time bins with a maximum visibility of 96.1% without correction for accidental coincidences. From the zeroth- to the third-order Franson interference, we infer an entanglement of formation (Eof) up to 1.89 ± 0.03 ebits—where 2 ebits is the maximal entanglement for a 4 × 4 dimensional biphoton—as a lower bound on the 61 time-bin BFC’s high-dimensional entanglement. To further characterize time-binned/frequency-binned BFCs we obtain Schmidt mode decompositions of BFCs generated using cavities with 45.32, 15.15, and 5.03 GHz FSRs. These decompositions confirm the time–frequency scaling from Fourier-transform duality. Moreover, we present the theory of conjugate Franson interferometry—because it is characterized by the state’s joint-temporal intensity (JTI)—which can further help to distinguish between pure-state BFC and mixed state entangled frequency pairs, although the experimental implementation is challenging and not yet available. In summary, our BFC serves as a platform for high-dimensional quantum information processing and high-dimensional quantum key distribution (QKD).

scholarly journals Entanglement between two gravitating universes

2021 ◽  
Author(s):  
Vijay Balasubramanian ◽  
Arjun Kar ◽  
Tomonori Ugajin
Keyword(s):  
Quantum Information ◽  
Analytic Continuation ◽  
Path Integral ◽  
Pure State ◽  
Entanglement Entropy ◽  
Replica Symmetry ◽  
Extremal Surface ◽  
Generalized Entropy ◽  
Two Universes ◽  
Effective Description

Abstract We study two disjoint universes in an entangled pure state. When only one universe contains gravity, the path integral for the n th Rényi entropy includes a wormhole between the n copies of the gravitating universe, leading to a standard “island formula” for entanglement entropy consistent with unitarity of quantum information. When both universes contain gravity, gravitational corrections to this configuration lead to a violation of unitarity. However, the path integral is now dominated by a novel wormhole with 2n boundaries connecting replica copies of both universes. The analytic continuation of this contribution involves a quotient by Ζ n replica symmetry, giving a cylinder connecting the two universes. When entanglement is large, this configuration has an effective description as a “swap wormhole”, a geometry in which the boundaries of the two universes are glued together by a “swaperator”. This description allows precise computation of a generalized entropy-like formula for entanglement entropy. The quantum extremal surface computing the entropy lives on the Lorentzian continuation of the cylinder/swap wormhole, which has a connected Cauchy slice stretching between the universes – a realization of the ER=EPR idea. The new wormhole restores unitarity of quantum information.

scholarly journals The QBIT Theory of Consciousness

2019 ◽  
Author(s):  
Majid Beshkar
Keyword(s):  
Information Theory ◽  
Quantum Mechanics ◽  
Quantum Information ◽  
Empirical Evidence ◽  
Pure State ◽  
External Stimulus ◽  
Information Theoretic ◽  
Scientific Disciplines ◽  
Pure States

The QBIT theory is an attempt toward solving the problem of consciousness based on empirical evidence provided by various scientific disciplines including quantum mechanics, biology, information theory, and thermodynamics. This theory formulates the problem of consciousness in the following four questions: (1) What is the nature of qualia? (2) How are qualia generated? (3) Why are qualia subjective? (4) Why does a quale have a particular quality or meaning?In sum, the QBIT theory proposes that (1) when a pack of quantum information is compressed beyond a certain threshold, a quale is generated; (2) a quale is a superdense pack of maximally entangled qubits in a pure state; (3) when information-theoretic certainty of a system about an external stimulus exceeds a particular level, the system becomes conscious of that stimulus; (4) subjectivity of consciousness is due to the fact that maximally entangled pure states are private and unshareable.

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