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Learning unknown processes affecting a quantum system reveals underlying physical mechanisms and enables suppression, mitigation, and correction of unwanted effects. Describing a general quantum process requires an exponentially large…

Understanding the noise affecting a quantum device is of fundamental importance for scaling quantum technologies. A particularly important class of noise models is that of Pauli channels, as randomized compiling techniques can effectively…

Quantum Physics · Physics 2025-05-19 Omar Fawzi , Aadil Oufkir , Daniel Stilck França

We show that entangled measurements provide an exponential advantage in sample complexity for Pauli channel estimation, which is both a fundamental problem and a practically important subroutine for benchmarking near-term quantum devices.…

Quantum Physics · Physics 2022-03-23 Senrui Chen , Sisi Zhou , Alireza Seif , Liang Jiang

We prove that adaptive strategies offer no advantage over non-adaptive ones for learning and testing Pauli channels using entangled inputs. This key observation allows us to characterize the query complexity for several fundamental tasks by…

Quantum Physics · Physics 2025-09-24 Xuan Du Trinh , Nengkun Yu

We discuss the estimation of channel parameters for a noisy quantum channel - the so-called Pauli channel - using finite resources. It turns out that prior entanglement considerably enhances the fidelity of the estimation when we compare it…

Quantum Physics · Physics 2009-11-07 Dietmar G. Fischer , Holger Mack , Markus A. Cirone , Matthias Freyberger

Here we revisit one of the prototypical tasks for characterizing the structure of noise in quantum devices: estimating every eigenvalue of an $n$-qubit Pauli noise channel to error $\epsilon$. Prior work [14] proved no-go theorems for this…

Quantum Physics · Physics 2025-09-16 Sitan Chen , Weiyuan Gong

The quantification of the entanglement present in a physical system is of para\-mount importance for fundamental research and many cutting-edge applications. Currently, achieving this goal requires either a priori knowledge on the system or…

We solve the problem of discriminating with minimum error probability two given Pauli channels. We show that, differently from the case of discrimination between unitary transformations, the use of entanglement with an ancillary system can…

Quantum Physics · Physics 2009-11-11 Massimiliano F. Sacchi

Entanglement depth quantifies how many qubits share genuine multipartite entanglement, but certification typically relies on tailored witnesses or full tomography, both of which scale poorly with system size. We recast entanglement-depth…

Quantum Physics · Physics 2025-12-16 Marcin Płodzień

We analyze the Pauli-channel estimation with mixed nonseparable states. It turns out that within a specific range entanglement can serve as a nonclassical resource. However, this range is rather small, that is entanglement is not very…

Quantum Physics · Physics 2009-11-07 Thorsten C. Bschorr , Dietmar G. Fischer , Matthias Freyberger

We study the problem of efficiently learning an unknown $n$-qubit unitary channel in diamond distance given query access. We present a general framework showing that if Pauli operators remain low-complexity under conjugation by a unitary,…

Quantum Physics · Physics 2026-04-07 Sabee Grewal , Daniel Liang

Quantum resources enable us to achieve an exponential advantage in learning the properties of unknown physical systems by employing quantum memory. While entanglement with quantum memory is recognized as a necessary qualitative resource,…

Quantum Physics · Physics 2026-02-26 Minsoo Kim , Changhun Oh

Understanding quantum noise is an essential step towards building practical quantum information processing systems. Pauli noise is a useful model that has been widely applied in quantum benchmarking, error mitigation, and error correction.…

Quantum Physics · Physics 2026-01-13 Senrui Chen , Zhihan Zhang , Liang Jiang , Steven T. Flammia

We show an experimental procedure to certify the classical capacity for noisy qubit channels. The method makes use of a fixed bipartite entangled state, where the system qubit is sent to the channel input and the set of local measurements…

Entanglement and entanglement-assisted are useful resources to enhance the mutual information of the Pauli channels, when the noise on consecutive uses of the channel has some partial correlations. In this Paper, we study…

Quantum Physics · Physics 2015-06-26 A. Fahmi , M. Golshani

Simulating noiseless quantum dynamics classically faces a fundamental dilemma: tensor-network methods become inefficient as entanglement saturates, while Pauli-truncation approaches typically rely on noise or randomness. To close the gap,…

Quantum Physics · Physics 2026-01-23 Jue Xu , Chu Zhao , Xiangran Zhang , Shuchen Zhu , Qi Zhao

We begin this thesis by expanding the technique of teleportation simulation, which adds noise to the entangled resource state to mimic channel effects. By introducing classical noise in the communication step, we show it is possible to…

Quantum Physics · Physics 2019-04-29 Thomas Cope

The unavoidable presence of noise is a crucial roadblock for the development of large-scale quantum computers and the ability to characterize quantum noise reliably and efficiently with high precision is essential to scale quantum…

Quantum Physics · Physics 2023-07-07 Cambyse Rouzé , Daniel Stilck França

Quantum error correction is instrumental in protecting quantum systems from noise in quantum computing and communication settings. Pauli channels can be efficiently simulated and threshold values for Pauli error rates under a variety of…

Quantum Physics · Physics 2017-04-25 Christopher Chamberland , Joel J. Wallman , Stefanie Beale , Raymond Laflamme

Entanglement is a key property in the development of quantum technologies and in the study of quantum many-body simulations. However, entanglement measurement typically requires quantum full-state tomography (FST). Here we present a neural…

Quantum Physics · Physics 2022-09-20 Yulei Huang , Liangyu Che , Chao Wei , Feng Xu , Xinfang Nie , Jun Li , Dawei Lu , Tao Xin
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