Quantum Journal

High-rate multipartite quantum secret sharing with composable security

Future quantum communication networks will conceivably support cryptographic tasks that require entanglement among more than two users. Quantum secret sharing is a prime example where entanglement provides a direct means to coordinate untrusted parties with security from eavesdropping in a multi-party setting. However, the canonical GHZ-based protocols can be vulnerable to participant attacks, in which untrusted parties try to learn the secret w...

Moment-Selective Quantum Designs in Aperiodic Temporal Ensembles

We introduce a general mechanism for engineering moment-selective temporal designs with hierarchically structured aperiodic drives. At special control settings where the driven dynamics is constrained by a finite symmetry group, lower-order moments can already reproduce Haar statistics while a selected higher-order deviation remains nonzero. A small static detuning from such a setting generically produces an exponentially long lifetime whose exp...

Structured Quantum Kernels for Chaotic Forecasting

Quantum kernels promise exponentially large feature spaces, but expressive circuits render their Gram matrices uninformative, bandwidth tuning collapses them toward classical RBF, and the practical consensus is that quantum kernels add nothing on classical data. We answer another productive question, an architectural one: whether the structure of an encoding circuit can carry an inductive bias that tuned classical kernels lack. We introduce AeRo...

Physical Counterexamples to the Wigner Shannon Entropy Conjecture

We construct physical quantum states with everywhere positive Wigner functions whose Shannon entropy lies below the vacuum value $1+\ln\pi$. Besides an explicit finite-energy counterexample, we obtain rank-two finite-Fock-support families with analytic positivity and entropy bounds. For fixed Fock level $n$ and coherence fraction $0\le\lambda<1$, the entropy difference satisfies $h(W)-(1+\ln\pi)=(2n-2^n\lambda^2)t^2+O_{n,\lambda}(t^4)$, yielding...