ANALYTIC ONE-BIT AND CNOT GATE CONSTRUCTIONS OF GENERAL n-QUBIT CONTROLLED GATES

2008 ◽  
Vol 06 (03) ◽  
pp. 447-462 ◽  
Author(s):  
YANG LIU ◽  
GUI LU LONG ◽  
YANG SUN

General n-qubit controlled unitary gates are frequently used in quantum information processing tasks. Barenco, Bennett, Cleve, Di Vincenzo, Margolus and Shor [Phys. Rev. A52 (1995) 3457] have given the general construction methods, and explicit results for up-to-four-qubits controlled unitary gates. We extended their calculation and gave two analytic expressions for the construction of general n-qubit controlled unitary gates in terms of one-qubit and two-qubit CNOT gates. There are two expressions – one is exponential in the qubit number which is efficient for up to ten qubits, and the other is polynomial in the qubit number, which is efficient for more than ten qubits.

2019 ◽  
Vol 17 (04) ◽  
pp. 1950031
Author(s):  
Jiaan Qi ◽  
Hui Khoon Ng

Randomized benchmarking (RB) is a popular procedure used to gauge the performance of a set of gates useful for quantum information processing (QIP). Recently, Proctor et al. [Phys. Rev. Lett. 119 (2017) 130502] demonstrated a practically relevant example where the RB measurements give a number [Formula: see text], very different from the actual average gate-set infidelity [Formula: see text], despite past theoretical assurances that the two should be equal. Here, we derive formulas for [Formula: see text], and for [Formula: see text] from the RB protocol, in a manner permitting easy comparison of the two. We show in general that, indeed, [Formula: see text], i.e. RB does not measure average infidelity, and, in fact, neither one bounds the other. We give several examples, all plausible in real experiments, to illustrate the differences in [Formula: see text] and [Formula: see text]. Many recent papers on experimental implementations of QIP have claimed the ability to perform high-fidelity gates because they demonstrated small [Formula: see text] values using RB. Our analysis shows that such a statement from RB alone has to be interpreted with caution.


2001 ◽  
Author(s):  
David P. DiVincenzo ◽  
Charles H. Bennett

2011 ◽  
Author(s):  
David G. Cory ◽  
Chandrasekhar Ramanathan ◽  
Raymond Laflamme ◽  
Joseph V. Emerson ◽  
Jonathan Baugh

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Jie Su ◽  
Xuchao Guo ◽  
Chengqi Liu ◽  
Shuhan Lu ◽  
Lin Li

AbstractQuantum image representation (QIR) is a necessary part of quantum image processing (QIP) and plays an important role in quantum information processing. To address the problems that NCQI cannot handle images with inconsistent horizontal and vertical position sizes and multi-channel image processing, an improved color digital image quantum representation (INCQI) model based on NCQI is proposed in this paper. The INCQI model can process color images and facilitate multi-channel quantum image transformations and transparency information processing of images using auxiliary quantum bits. In addition, the quantum image control circuit was designed based on INCQI. And quantum image preparation experiments were conducted on IBM Quantum Experience (IBMQ) to verify the feasibility and effectiveness of INCQI quantum image preparation. The prepared image information was obtained by quantum measurement in the experiment, and the visualization of quantum information was successfully realized. The research in this paper has some reference value for the research related to QIP.


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