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Accurately estimating high-order moments of quantum states is an elementary precondition for many crucial tasks in quantum computing, such as entanglement spectroscopy, entropy estimation, spectrum estimation, and predicting non-linear…

Quantum Physics · Physics 2024-05-16 Benchi Zhao , Mingrui Jing , Lei Zhang , Xuanqiang Zhao , Yu-Ao CHen , Kun Wang , Xin Wang

We present a probabilistic scheme for generating and purifying maximally-entangled states of two atoms inside an optical cavity via no-photon detection in the output cavity mode, where ideal detectors may not be required. The intermediate…

Quantum Physics · Physics 2009-11-10 P. Lougovski , E. Solano , H. Walther

While the preparation of a general quantum state is challenging, realistic problem instances, such as those encountered in quantum chemistry and quantum machine learning-typically exhibit hierarchical amplitude structures, consisting of a…

Quantum Physics · Physics 2026-01-15 Yue Wang , Xiao-Ming Zhang , Xiao Yuan , Qi Zhao

We propose a quantum key distribution scheme which closely matches the performance of a perfect single photon source. It nearly attains the physical upper bound in terms of key generation rate and maximally achievable distance. Our scheme…

Quantum Physics · Physics 2007-10-15 Wolfgang Mauerer , Christine Silberhorn

We discuss several methods to produce superpositions of optical coherent states (also known as "cat states"). Cat states have remarkable properties that could allow them to be powerful tools for quantum information processing and metrology.…

Quantum Physics · Physics 2009-11-13 S. Glancy , H. M. Vasconcelos

Existing quantum cryptographic schemes are not, as they stand, operable in the presence of noise on the quantum communication channel. Although they become operable if they are supplemented by classical privacy-amplification techniques, the…

Quantum Physics · Physics 2009-01-23 D. Deutsch , A. Ekert , R. Jozsa , C. Macchiavello , S. Popescu , A. Sanpera

Photonic quantum metrology harnesses quantum states of light, such as NOON or Twin-Fock states, to measure unknown parameters beyond classical precision limits. Current protocols suffer from two severe limitations that preclude their…

In quantum communication via noisy channels, the error probability scales exponentially with the length of the channel. We present a scheme of a quantum repeater that overcomes this limitation. The central idea is to connect a string of…

Quantum Physics · Physics 2007-05-23 H. -J. Briegel , W. Dür , J. I. Cirac , P. Zoller

The quantum component in uncertainty relation can be naturally characterized by the quantum coherence of a quantum state, which is of paramount importance in quantum information science. Here, we experimentally investigate quantum…

Quantum Physics · Physics 2022-04-25 Lu Liu , Ting Zhang , Xiao Yuan , He Lu

It is shown that a realistic, controlled bidirectional remote state preparation is possible using a large class of entangled quantum states having a particular structure. Existing protocols of probabilistic, deterministic and joint remote…

Quantum Physics · Physics 2022-06-10 Vishal Sharma , Chitra Shukla , Subhashish Banerjee , Anirban Pathak

Photon subtraction can enhance entanglement, which for pure states induces a decrease in the purity of reduced states. In contrast, by analyzing the purities of Gaussian states before and after subtracting a single photon, we prove that the…

Quantum Physics · Physics 2024-09-06 Kun Zhang , Huijun Li , Jietai Jing , Nicolas Treps , Mattia Walschaers

In this paper, we have reinvestigated probabilistic quantum communication protocols and developed a nontraditional remote state preparation protocol that allows for deterministically transferring information encoded in quantum states using…

Quantum Physics · Physics 2023-05-24 Xuanxuan Xin , Yongxing Li , Shiwen He , Chong Li

A candidate application for quantum computers is to simulate the low-temperature properties of quantum systems. For this task, there is a well-studied quantum algorithm that performs quantum phase estimation on an initial trial state that…

Quantum Physics · Physics 2024-11-04 Chi-Fang , Chen , Alexander M. Dalzell , Mario Berta , Fernando G. S. L. Brandão , Joel A. Tropp

The preparation stage of optical qubits is an essential task in all the experimental setups employed for the test and demonstration of Quantum Optics principles. We consider a deterministic protocol for the preparation of qubits as a…

Quantum Physics · Physics 2015-06-19 Nicola Dalla Pozza , Howard M. Wiseman , Elanor H. Huntington

It is shown that a large class of weak disturbances on macroscopic quantum superpositions can be canceled by a probabilistic reversing operation on the system. We illustrate this for spin systems undergoing an Ising-type interaction with…

Quantum Physics · Physics 2009-11-13 Hiroaki Terashima , Masahito Ueda

We present two efficient quantum key distribution schemes over two different collective-noise channels. The accepted hypothesis of collective noise is that photons travel inside a time window small compared to the variation of noise.…

Quantum Physics · Physics 2009-11-13 Xi-Han Li , Fu-Guo Deng , Hong-Yu Zhou

In this paper, we propose a novel bipartite entanglement purification protocol built upon hashing and upon the guessing random additive noise decoding (GRAND) approach recently devised for classical error correction codes. Our protocol…

Quantum Physics · Physics 2024-09-25 André Roque , Diogo Cruz , Francisco A. Monteiro , Bruno C. Coutinho

The concept of asymptotic correctability of Bell-diagonal quantum states is generalised to elementary quantum systems of higher dimensions. Based on these results basic properties of quantum state purification protocols are investigated…

Quantum Physics · Physics 2007-05-23 Kedar S. Ranade , Gernot Alber

Quantum non-Gaussian states represent an important class of highly non-classical states whose preparation requires quantum operations or measurements beyond the class of Gaussian operations and statistical mixing. Here we derive criteria…

Quantum Physics · Physics 2021-07-21 Jaromír Fiurášek , Lukáš Lachman , Radim Filip

Postselected quantum computation is distinguished from regular quantum computation by accepting the output only if measurement outcomes satisfy predetermined conditions. The output must be accepted with nonzero probability. Methods for…

Quantum Physics · Physics 2007-05-23 E. Knill