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Many quantum algorithms make use of ancilla, additional qubits used to store temporary information during computation, to reduce the total execution time. Quantum computers will be resource-constrained for years to come so reducing ancilla…

Quantum Physics · Physics 2020-02-26 Jonathan M. Baker , Casey Duckering , Frederic T. Chong

In 2004, Cuccaro et al found a quantum-quantum adder with $O(n)$ gate cost and $O(1)$ ancilla qubits. Since then, it's been an open question whether classical-quantum adders can achieve the same asymptotic complexity. These costs are…

Quantum Physics · Physics 2025-08-01 Craig Gidney

We formulate and numerically simulate the single control qubit Shor algorithm for the case of static imperfections induced by residual couplings between qubits. This allows us to study the accuracy of Shor's algorithm with respect to these…

Quantum Physics · Physics 2008-12-15 Ignacio Garcia-Mata , Klaus M. Frahm , Dima L. Shepelyansky

We present a general decomposition of the Generalized Toffoli, and for completeness, the multi-target gate using an arbitrary number of clean or dirty ancilla. While prior work has shown how to decompose the Generalized Toffoli using 0, 1,…

Quantum Physics · Physics 2019-04-04 Jonathan M. Baker , Casey Duckering , Alexander Hoover , Frederic T. Chong

An algorithm is given to factor an integer with $N$ digits in $\ln^m N$ steps, with $m$ approximately 4 or 5. Textbook quadratic sieve methods are exponentially slower. An improvement with the aid of an a particular function would provide a…

General Physics · Physics 2007-05-23 Gordon Chalmers

By how much must the communication complexity of a function increase if we demand that the parties not only correctly compute the function but also return all registers (other than the one containing the answer) to their initial states at…

Quantum Physics · Physics 2016-12-07 Harry Buhrman , Matthias Christandl , Christopher Perry , Jeroen Zuiddam

We propose an adiabatic quantum algorithm capable of factorizing numbers, using fewer qubits than Shor's algorithm. We implement the algorithm in an NMR quantum information processor and experimentally factorize the number 21. Numerical…

Quantum Physics · Physics 2009-11-13 Xinhua Peng , Zeyang Liao , Nanyang Xu , Gan Qin , Xianyi Zhou , Dieter Suter , Jiangfeng Du

We first show how to construct an O(n)-depth O(n)-size quantum circuit for addition of two n-bit binary numbers with no ancillary qubits. The exact size is 7n-6, which is smaller than that of any other quantum circuit ever constructed for…

Quantum Physics · Physics 2011-06-17 Yasuhiro Takahashi , Seiichiro Tani , Noboru Kunihiro

The assumed computationally difficulty of factoring large integers forms the basis of security for RSA public-key cryptography, which specifically relies on products of two large primes or semi-primes. The best-known factoring algorithms…

Cryptography and Security · Computer Science 2019-10-24 Michele Mosca , Sebastian R. Verschoor

This work is a tutorial on Shor's factoring algorithm by means of a worked out example. Some basic concepts of Quantum Mechanics and quantum circuits are reviewed. It is intended for non-specialists which have basic knowledge on…

Quantum Physics · Physics 2007-05-23 C. Lavor , L. R. U. Manssur , R. Portugal

Tomography has reached its practical limits in characterization of new quantum devices, and there is a need for a new means of characterizing and validating new technological advances in this field. We propose a different verification…

Quantum Physics · Physics 2013-11-15 Omar Gamel , Daniel F. V. James

Shor's factoring algorithm (SFA) finds the prime factors of a number, $N=p_1 p_2$, exponentially faster than the best known classical algorithm. Responsible for the speed-up is a subroutine called the quantum order finding algorithm (QOFA)…

Quantum Physics · Physics 2015-01-14 Thomas Lawson

We propose a semiclassical version of Shor's quantum algorithm to factorize integer numbers, based on spin-1/2 SU(2) generalized coherent states. Surprisingly, we find evidences that the algorithm's success probability is not too severely…

Quantum Physics · Physics 2009-11-10 Paolo Giorda , Alfredo Iorio , Samik Sen , Siddhartha Sen

A quantum processor (QuP) can be used to exploit quantum mechanics to find the prime factors of composite numbers[1]. Compiled versions of Shor's algorithm have been demonstrated on ensemble quantum systems[2] and photonic systems[3-5],…

We present improved quantum circuit for modular exponentiation of a constant, which is the most expensive operation in Shor's algorithm for integer factorization. While previous work mostly focuses on minimizing the number of qubits or the…

Quantum Physics · Physics 2023-11-28 Xia Liu , Huan Yang , Li Yang

The Quantum Fourier Transform (QFT) is a fundamental component of many quantum computing algorithms. In this paper, we present an alternative method for factoring this transformation. Inspired by this approach, we introduce a new quantum…

Quantum Physics · Physics 2025-07-30 Juan M. Romero , Emiliano Montoya-González , Guillermo Cruz , Roberto C. Romero

Quantum oracles are widely adopted in problems, like query oracle in Grover's algorithm, cipher in quantum cryptanalytic and data encoder in quantum machine learning. Notably, the bit-flip oracle, capable of flipping the state based on a…

Quantum Physics · Physics 2025-12-02 Buji Xu , Junhong Nie , Xiaoming Sun

Typical circuit implementations of Shor's algorithm involve controlled rotation gates of magnitude $\pi/2^{2L}$ where $L$ is the binary length of the integer N to be factored. Such gates cannot be implemented exactly using existing…

Quantum Physics · Physics 2007-05-23 Austin G. Fowler , Lloyd C. L. Hollenberg

Reversible circuits for modular multiplication $Cx$%$M$ with $x<M$ arise as components of modular exponentiation in Shor's quantum number-factoring algorithm. However, existing generic constructions focus on asymptotic gate count and…

Emerging Technologies · Computer Science 2015-04-06 Igor L. Markov , Mehdi Saeedi

We propose a quantum algorithm for the purification of a generic mixed state $\rho$ of a $n$-qudit system by using an ancillary $n$-qudit system. The algorithm is optimal in that (i) the number of ancillary qudits cannot be reduced, (ii)…

Quantum Physics · Physics 2009-05-04 Giuliano Benenti , Giuliano Strini