14 citations · 33 across the 16 of their papers we have counts for
20 papers
Computational entanglement distillation beyond pure states: efficient protocols and fundamental limitations
Takeru Utsumi, Jacopo Rizzo, Ryuji Takagi +1
The information-theoretic approach to entanglement typically relies on arbitrarily many input copies and unboundedly complex operations; however, the available resources are constr…
Universal distillation of quantum entanglement
Ryuji Takagi, Kaito Watanabe, Takaya Matsuura +2
Distillable entanglement---the maximum rate of Bell states extractable from the given noisy entangled states via local operations and classical communication (LOCC)---has been a ce…
When Classical Correlations Certify Entanglement Recovery
Takeru Utsumi, Yota Tachibana, Yoshifumi Nakata +4
Entanglement and state distinguishability have long been central topics in quantum foundations. While each has developed into a rich subject in its own right, they can be connected…
All you need is the universal correlation detector: A unified approach to universalize communication protocols over quantum channels
Kaito Watanabe, Takaya Matsuura, Ryuji Takagi
Constructing optimal quantum information protocols without complete knowledge of the underlying states or channels is a central challenge. We address this challenge by developing u…
Scaling-optimal purification of noisy qubit unitary channels
Ryotaro Niwa, Satoshi Yoshida, Koki Ono +5
We consider the problem of purifying noisy qubit unitary channels. Given the ability to apply an unknown qubit unitary channel followed by depolarizing noise, we aim to construct a…
Reliability of asymptotic work extraction
Kaito Watanabe, Bartosz Regula, Marco Tomamichel +1
Extracting work from quantum states is a fundamental task in quantum thermodynamics. Previous studies have primarily focused on determining the best achievable rate of work extract…
Asymptotic magic state distillation with almost linear rate
Koki Ehara, Ryuji Takagi
The overhead exponent -- characterizing the scaling of the number of noisy magic states with respect to the target distillation error -- has been a central quantity to benchmark ma…
Universal quantum resource distillation via composite generalised quantum Stein's lemma
Ludovico Lami, Bartosz Regula, Ryuji Takagi
The performance of quantum resource manipulation protocols, including key examples such as distillation of quantum entanglement, is measured in terms of the rate at which desired t…
Weak distillation of quantum resources
Shinnosuke Onishi, Oliver Hahn, Ryuji Takagi
Importance sampling based on quasi-probability decomposition is the backbone of many widely used techniques, such as error mitigation, circuit knitting, and, more generally, virtua…
Random dilation superchannel
Satoshi Yoshida, Ryotaro Niwa, Takeru Utsumi +2
We present a quantum circuit that implements the random dilation superchannel, transforming parallel queries of an unknown quantum channel into the same number of parallel queries…
Recovery of the second law in fully quantum thermodynamics
Naoto Shiraishi, Ryuji Takagi
Quantum thermodynamics investigates how robust the second law of thermodynamics serves as the unique fundamental law in the small quantum world. To tackle this problem, the quantum…
Quantum algorithms for Uhlmann transformation
Takeru Utsumi, Yoshifumi Nakata, Qisheng Wang +1
Uhlmann's theorem is a central result in quantum information theory, which associates the closeness of two quantum states with that of their purifications. The theorem also well ch…
Measuring non-Gaussianity with Correlation
Oliver Hahn, Ryuji Takagi
Quantum non-Gaussianity is a key resource for quantum advantage in continuous-variable systems. We introduce a general framework to quantify non-Gaussianity based on correlation ge…
Universal tradeoff relations between resource cost and irreversibility of channels: General-resource Wigner-Araki-Yanase theorems and beyond
Hiroyasu Tajima, Koji Yamaguchi, Ryuji Takagi +1
Quantum technologies offer exceptional -- sometimes almost magical -- speed and performance, yet every quantum process costs physical resources. Designing next-generation quantum d…
Universal work extraction in quantum thermodynamics
Kaito Watanabe, Ryuji Takagi
Evaluating the maximum amount of work extractable from a nanoscale quantum system is one of the central problems in quantum thermodynamics. Previous works identified the free energ…
Symmetric channel verification for purifying noisy quantum channels
Kento Tsubouchi, Yosuke Mitsuhashi, Ryuji Takagi +1
Symmetry inherent in quantum states has been widely used to reduce the effect of noise in quantum error correction and a quantum error mitigation technique known as symmetry verifi…
Bridging magic and non-Gaussian resources via Gottesman-Kitaev-Preskill encoding
Oliver Hahn, Giulia Ferrini, Ryuji Takagi
Although the similarity between non-stabilizer states -- also known as magic states -- in discrete-variable systems and non-Gaussian states in continuous-variable systems has widel…
Classical simulation and quantum resource theory of non-Gaussian optics
Oliver Hahn, Ryuji Takagi, Giulia Ferrini +1
We propose efficient algorithms for classically simulating Gaussian unitaries and measurements applied to non-Gaussian initial states. The constructions are based on decomposing th…
Gibbs-preserving operations requiring infinite amount of quantum coherence
Hiroyasu Tajima, Ryuji Takagi
Gibbs-preserving operations have been studied as one of the standard free processes in quantum thermodynamics. Although they admit a simple mathematical structure, their operationa…
Quantum Dynamic Programming
Jeongrak Son, Marek Gluza, Ryuji Takagi +1
We introduce a quantum extension of dynamic programming, a fundamental computational method that efficiently solves recursive problems using memory. Our innovation lies in showing…