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Quantum control is an essential tool for the operation of quantum technologies such as quantum computers, simulators, and sensors. Although there are sophisticated theoretical tools for developing quantum control protocols, formulating…

Quantum Physics · Physics 2013-04-02 Hanhan Li , Alireza Shabani , Mohan Sarovar , Birgitta K. Whaley

We assess the quality of a source of allegedly pure two-qubit states using both standard tomography and methods inspired by device-independent self-testing. Even when the detection and locality loopholes are open, the latter methods can…

Quantum Physics · Physics 2019-08-08 Koon Tong Goh , Chithrabhanu Perumangatt , Zhi Xian Lee , Alexander Ling , Valerio Scarani

We discuss recent developments in measurement protocols that generate quantum entanglement between two remote qubits, focusing on the theory of joint continuous detection of their spontaneous emission. We consider a device geometry similar…

In classical control theory, tracking refers to the ability to perform measurements and feedback on a classical system in order to enforce some desired dynamics. In this paper we investigate a simple version of quantum tracking, namely, we…

Quantum Physics · Physics 2008-11-20 Paulo E. M. F. Mendonca , Alexei Gilchrist , Andrew C. Doherty

Certifying quantum behavior from classically accessible data is essential for secure communication and scalable quantum technologies. While powerful certification methods such as Bell nonlocality and quantum steering exist, their…

Implementing fast and high-fidelity quantum operations using open-loop quantum optimal control relies on having an accurate model of the quantum dynamics. Any deviations between this model and the complete dynamics of the device, such as…

Quantum Physics · Physics 2024-10-31 Elie Genois , Noah J. Stevenson , Noah Goss , Irfan Siddiqi , Alexandre Blais

Entanglement is the quintessential quantum mechanical phenomenon understood to lie at the heart of future quantum technologies and the subject of fundamental scientific investigations. Mixture, resulting from noise, is often an unwanted…

We use hyper-entanglement to experimentally realize deterministic entanglement swapping based on quantum Elegant Joint Measurements. These are joint projections of two qubits onto highly symmetric, iso-entangled, bases. We report…

We present a quantum circuit that transforms an unknown three-qubit state into its canonical form, up to relative phases, given many copies of the original state. The circuit is made of three single-qubit parametrized quantum gates, and the…

Superdense Coding is a cornerstone in secure quantum communication, exploiting pre-shared entanglement to encode two classical bits within a single qubit. However, noise and decoherence deteriorate entanglement quality, restricting both…

Quantum Physics · Physics 2025-04-18 Syed Emad Uddin Shubha , Tasnuva Farheen

Harnessing the advantages of shared entanglement for sending quantum messages often requires the implementation of complex two-particle entangled measurements. We investigate entanglement advantages in protocols that use only the simplest…

Two qubits in pure entangled states going through separate paths and interacting with their own individual environments will gradually lose their entanglement. Here we show that the entanglement change of a two-qubit state due to amplitude…

Quantum Physics · Physics 2014-01-23 Wei Song , Ming Yang , Zhuo-Liang Cao

While it has recently been demonstrated how to certify the maximal amount of randomness from any pure two-qubit entangled state in a device-independent way [E. Woodhead et al., Phys. Rev. Research 2, 042028(R)(2020)], the problem of optimal…

Quantum coherence is the key resource for quantum technology, with applications in quantum optics, information processing, metrology and cryptography. Yet, there is no universally efficient method for quantifying coherence either in…

Quantum Physics · Physics 2014-10-24 Davide Girolami

We propose a novel double-entanglement-based quantum cryptography protocol that is both efficient and deterministic. The proposal uses photon pairs with entanglement both in polarization and in time degrees of freedom; each measurement in…

Quantum Physics · Physics 2009-11-11 Zeng-Bing Chen , Qiang Zhang , Xiao-Hui Bao , J. Schmiedmayer , Jian-Wei Pan

Certifying that an n-qubit state synthesized in the lab is close to the target state is a fundamental task in quantum information science. However, existing rigorous protocols either require deep quantum circuits or exponentially many…

Quantum Physics · Physics 2024-04-12 Hsin-Yuan Huang , John Preskill , Mehdi Soleimanifar

We propose practical and efficient protocols for verifying bipartite pure states for any finite dimension, which can also be applied to fidelity estimation. Our protocols are based on adaptive local projective measurements with either…

Quantum Physics · Physics 2019-09-18 Zihao Li , Yun-Guang Han , Huangjun Zhu

Detection of entanglement in quantum networks consisting of many parties is one of the important steps towards building quantum communication and computation networks. We consider a scenario where the measurement devices used for this…

Quantum Physics · Physics 2017-05-03 Ivan Šupić , Paul Skrzypczyk , Daniel Cavalcanti

Extracting information from quantum devices has long been a crucial problem in the field of quantum mechanics. By performing elaborate measurements, quantum state tomography, an important and fundamental tool in quantum science and…

Quantum Physics · Physics 2022-06-24 Yu Wang , Keren Li

Distinguishing physical processes is one of the fundamental problems in quantum physics. Although distinguishability of quantum preparations and quantum channels have been studied considerably, distinguishability of quantum measurements…

Quantum Physics · Physics 2021-04-13 Chandan Datta , Tanmoy Biswas , Debashis Saha , Remigiusz Augusiak
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