Researchers develop a quantum circuit framework for extended Wigner's friend scenarios, resolving logical paradoxes by tracking Heisenberg cuts.

This paper presents a curated selection of research questions at the intersection of quantum gravity and quantum information, chosen to highlight issues that we regard as particularly important for…

Can causal relations be subject to quantum indefiniteness, similar to other physical properties? The process-matrix framework formalises this possibility: valid processes are defined by what local lab...

Incompatible quantum channels cannot be jointly and exactly realized, meaning that any approximate joint realization inevitably entails a tradeoff in implementation accuracy. While this notion of chan...

Karol Horodecki, Leonard Sikorski, Siddhartha Das, and Mark M. Wilde, Quantum 10, 2098 (2026). In this paper, we develop the resource theory of quantum secret key. Operating under the assumption that...

The group of CQT Fellow Nelly Ng and collaborators find conditions that make quantum catalysts fully reusable

Takeru Utsumi and Yoshifumi Nakata, Quantum 10, 2024 (2026). Reliably transmitting quantum information via a noisy quantum channel is a central challenge in quantum information science. While constructing...

Certifying that quantum randomness generated by untrusted devices is unpredictable to an attacker (say, Eve) is crucial for device-independent security. Bipartite protocols where only one of the parti...

はじめに 量子状態識別問題がSDPとして定式化されていく流れを前回の記事で議論しました。 本記事では、このSDPをPythonで数値的に解く方法を解説していきます。 参考文献 以下の本がCVXPYを使ったPythonでの凸最適化の勉強にとってもなります。 寒野善博...

Lewis Wooltorton, Peter Brown, and Roger Colbeck, Quantum 9, 1930 (2025). Nonlocal tests on multi-partite quantum correlations form the basis of protocols that certify randomness in a device-independent...

In quantum systems with infinitely many degrees of freedom, states can be infinitely entangled across a pair of subsystems, but are there different forms of infinite entanglement? To understand entang...

量子基礎論

For a class of quantum systems that exhibit contextuality, a rigorous theoretical connection between anomalous heat flow and quantumness is established, thereby opening avenues to explore nonclassical...

Quasiprobability representations are well-established tools in quantum information science, with applications ranging from the classical simulability of quantum computation to quantum process tomograp...

Thermal operations are quantum channels that have taken a prominent role in deriving fundamental thermodynamic limitations in quantum systems. We show that these channels are uniquely characterized by...

This work is an extention of Shiraishi and Matsumoto [10], and discusses the computational complexity of the long-term average of local observables in one-dimensional lattices with shift-invariant nea...

We consider quantum systems with energy constraints relative to a reference Hamiltonian. In general, quantum channels and continuous-time dynamics need not satisfy energy conservation. Physically mean...

The problem of specifying the optimum quantum detector in multiple hypotheses testing is considered for application to optical communications. The quantum digital detection problem is formulated as a ...

Long-range quantum systems, in which the interactions decay as $1/r^α$, are of increasing interest due to the variety of experimental set-ups in which they naturally appear. Motivated by this, we stud...

To understand the emergence of macroscopic irreversibility from microscopic reversible dynamics, the idea of coarse-graining plays a fundamental role. In this work, we focus on the concept of macrosco...

YouTube video by Francesco Buscemi

Implementing the time evolution under a desired target Hamiltonian is critical for various applications in quantum science. Due to the exponential increase of parameters in the system size and due to ...

The Clifford group plays a central role in quantum information science. It is the building block for many error-correcting schemes and matches the first three moments of the Haar measure over the unit...

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We introduce a definition of coarse-grained entropy that unifies measurement-based (observational entropy) and max-entropy-based (Jaynes) approaches to coarse-graining, by identifying physical constra...

npj Quantum Information - High-dimensional entanglement witnessed by correlations in arbitrary bases

An operational description of quantum phenomena concerns developing models that describe experimentally observed behaviour. $\textit{Higher-order quantum operations}\unicode{x2014}$quantum operations ...

量子基礎論

This work investigates the consequences of assuming that the quantum measurement process -- i.e., the physical realization of a measurement through an interaction between the system to be measured wit...

Landauer's limit on heat dissipation during information erasure is critical as devices shrink, requiring optimal pure-state preparation to minimize errors. However, Nernst's third law states this dema...

Novel bounds on the equilibration of observables in isolated quantum systems help resolve the apparent contradiction between the second law of thermodynamics and unitary evolution.