Teleportation through time-varying channels: threshold geometry and a complete-positivity bound on non-Markovian backflow

• URL: http://arxiv.org/abs/2608.11314v1
• Date: Tue, 11 Aug 2026 18:03:16 GMT
• Title: Teleportation through time-varying channels: threshold geometry and a complete-positivity bound on non-Markovian backflow
• Abstract summary: A Bell pair distributed through a link has dynamics that separate into a fixed part and a moving one.<n>The negativity, fully entangled fraction, discord, and average teleportation fidelity depend on time only through the accumulated damping parameters.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: A Bell pair distributed through a link that combines amplitude damping with dephasing at time-dependent rates has dynamics that separate into a fixed part and a moving one. The negativity, fully entangled fraction, discord, and average teleportation fidelity depend on time only through the accumulated damping parameters $p(t)$ and $q(t)$. Every threshold is therefore a curve fixed in the unit square, and the rates select nothing but a trajectory across it. The Horodecki fidelity formula $\bar{F} = \frac{1}{2} + \frac{1}{6}\mathrm{Tr}|T|$ covers one- and two-sided exposure alike: the condition $\det T \leq 0$ under which it takes this form holds throughout the unit square for both. Under symmetric two-sided noise the entanglement vanishes when $p+q\geq1$, where the exact relation $\bar{F}^{2s}=\frac{2}{3}+\frac{1}{3}\mathcal{N}_{2s}$ ties disentanglement and the loss of quantum advantage to the same instant. One-sided exposure admits no finite-time sudden death for any rate profile, and the discord stays strictly positive throughout the open square, so the distributed state can be separable, useless for teleportation, and still nonclassical. For harmonically modulated rates, complete positivity caps the backflow at one modulation period of static decay, $ΔΓ_{k}\leq2πγ_{k,0}/Ω$, equivalently at a modulation depth $ξ_{k}\leq4.6033$ independent of $Ω$. Inside that window the trajectory reverses, producing finite intervals of restored quantum advantage and entanglement sudden birth.

Related papers

• Constrained Online Learning with Noisy Constraint Values [55.29259818039367]
  Under common feasibility, our LEDGER algorithm attains $O(sqrt T)$ expected regret and $O(sqrtTlog(eT))$ expected budget violation.<n>Neither a Slater condition, independence between feedback channels, nor an absolute constraint-value bound is needed.
  arXiv  Detail & Related papers  (2026-09-07T01:38:41Z)
• Restricted Eigenvalues Beyond Gaussian Width: Threshold Occupancy under Heavy Tails [47.36630149538994]
  For isotropic sub-Gaussian measurements, the benchmark sample size is $1+w(A)2$, where $w(A)$ is the Gaussian width of the normalized descent cone.<n>We give an explicit and systematic negative answer to the general question as formulated there: the proposed law fails in its full dimension-free, arbitrary-set form.<n>Under isotropy, a distribution-free fallback governed by affine dimension times squared enclosing radius is sharp on this family.
  arXiv  Detail & Related papers  (2026-09-03T08:05:05Z)
• Collective photon echoes in the Tavis-Cummings model: distribution independence, two detuning regimes, and the Dicke ladder [0.0]
  An ensemble of molecules prepared in its ground state and sharing a cavity with a weak field does not simply absorb.<n>The intensity collapses and then recurs, in a train of collective photon echoes.<n>A feasibility analysis against a five-qubit superconducting device, with Lindblad simulations of cavity decay and dephasing and full-Hilbert-space disorder simulations, shows the first echoes observable at $Nsim5$-$20$ on existing hardware.
  arXiv  Detail & Related papers  (2026-08-18T21:36:21Z)
• The Decoherence Exponent: Stable Phase Noise and Constraints on Objective State Reduction [0.0]
  Averaging $eiL_uQ$ gives a completely positive dephasing semigroup.<n>Schoenberg's theorem ensures complete positivity for any finite real spectrum when $0le2$.<n>For a bounded reduction walk, we prove Born probabilities for every symmetric bounded proposal law.
  arXiv  Detail & Related papers  (2026-08-18T21:36:16Z)
• Testing edge chirality with a three-path fractional quantum Hall interferometer [0.0]
  We propose an average-current interferometer for the directional causal response of fractional quantum Hall edges.<n>Three coherent quantum point contacts (QPCs) form a flux-enclosing loop, so the leading Aharonov-Bohm harmonic is cubic in tunneling.
  arXiv  Detail & Related papers  (2026-07-27T13:56:36Z)
• Avoiding unsafe sets when training with Langevin Dynamics [1.0762008415887194]
  We study the shape-free bound $_t(mathcalA_H) le (mathcalA_H) le (mathcalA_H) le (mathcalA_H) le (mathcalA_H) le (mathcalA_H) le (mathcalA_H) le (mathcalA_H)
  arXiv  Detail & Related papers  (2026-07-08T15:36:45Z)
• Uniform-in-Time Weak Propagation-of-Chaos in Shallow Neural Networks [37.451796388624864]
  We find uniform-in-time bounds for $|f__tMF- f_hat_tm|2 lesssim textpoly(d/)$ neurons, training samples, and GD steps.<n>A key takeaway of our result is that whenever the convergence rate of the mean-field, population-loss dynamics is faster than $t-2$, we can attain a loss of $$ with only $textpoly(d/)$ neurons, training samples, and GD steps.
  arXiv  Detail & Related papers  (2026-05-21T05:14:19Z)
• Universal Quantum Suppression in Frustrated Ising Magnets across the Quasi-1D to 2D Crossover via Quantum Annealing [0.0]
  competing ferromagnetic and antiferromagnetic couplings generate a sign problem provably intractable for quantum Monte Carlo at any system size.<n>We measure quantum-driven transitions at $g_cmathrmQPUin0.286,,0.210,,0.156,,0.093$ for $in1.0,,0.7,,0.5,,0.3$.
  arXiv  Detail & Related papers  (2026-03-25T13:50:52Z)
• Floquet Recurrences in the Double Kicked Top [0.0]
  We study exact quantum recurrences in the double kicked top (DKT)<n>We analytically show exact periodicity of the Floquet operator for $k_r = j/2$ and $k_r = j/4$.<n>Our work demonstrates that regular and chaotic regimes can be controlled for any system size by tuning $k_r$ and $k_$.
  arXiv  Detail & Related papers  (2025-11-17T13:10:45Z)
• Unexpected non-universality of the time braiding phase of anyons tied by the scaling dimension [45.88028371034407]
  We use a braiding nonequilibrium fluctuation dissipation relation linking the DC noise to the response function inferred from the braiding constraint in the time-domain.<n>This questions the universality of $theta$ that can reflect the microscopic edge dynamics, in contrast to the topologically protected braiding phase in the space domain.
  arXiv  Detail & Related papers  (2025-10-23T14:18:15Z)
• Mesoscopic Fluctuations and Multifractality at and across Measurement-Induced Phase Transition [46.176861415532095]
  We explore statistical fluctuations over the ensemble of quantum trajectories in a model of two-dimensional free fermions.<n>Our results exhibit a remarkable analogy to Anderson localization, with $G_AB$ corresponding to two-terminal conductance.<n>Our findings lay the groundwork for mesoscopic theory of monitored systems, paving the way for various extensions.
  arXiv  Detail & Related papers  (2025-07-15T13:44:14Z)
• Dynamically emergent correlations in bosons via quantum resetting [0.0]
  We study the nonequilibrium stationary state (NESS) induced by quantum resetting of a system of $N$ noninteracting bosons in a harmonic trap.<n>We fully characterize the steady state by analytically computing several physical observables such as the average density, extreme value statistics, order and gap statistics.<n>This is a rare example of a strongly correlated quantum many-body NESS where various observables can be exactly computed.
  arXiv  Detail & Related papers  (2024-07-29T18:00:35Z)
• On the $O(\rac{\sqrt{d}}{T^{1/4}})$ Convergence Rate of RMSProp and Its Momentum Extension Measured by $\ell_1$ Norm [54.28350823319057]
  This paper considers the RMSProp and its momentum extension and establishes the convergence rate of $frac1Tsum_k=1T.<n>Our convergence rate matches the lower bound with respect to all the coefficients except the dimension $d$.<n>Our convergence rate can be considered to be analogous to the $frac1Tsum_k=1T.
  arXiv  Detail & Related papers  (2024-02-01T07:21:32Z)
• Random quantum circuits transform local noise into global white noise [118.18170052022323]
  We study the distribution over measurement outcomes of noisy random quantum circuits in the low-fidelity regime. For local noise that is sufficiently weak and unital, correlations (measured by the linear cross-entropy benchmark) between the output distribution $p_textnoisy$ of a generic noisy circuit instance shrink exponentially. If the noise is incoherent, the output distribution approaches the uniform distribution $p_textunif$ at precisely the same rate.
  arXiv  Detail & Related papers  (2021-11-29T19:26:28Z)
• Anisotropy-mediated reentrant localization [62.997667081978825]
  We consider a 2d dipolar system, $d=2$, with the generalized dipole-dipole interaction $sim r-a$, and the power $a$ controlled experimentally in trapped-ion or Rydberg-atom systems. We show that the spatially homogeneous tilt $beta$ of the dipoles giving rise to the anisotropic dipole exchange leads to the non-trivial reentrant localization beyond the locator expansion.
  arXiv  Detail & Related papers  (2020-01-31T19:00:01Z)

This list is automatically generated from the titles and abstracts of the papers in this site.

This site does not guarantee the quality of this site (including all information) and is not responsible for any consequences.