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The best known size lower bounds against unrestricted circuits have remained around $3n$ for several decades. Moreover, the only known technique for proving lower bounds in this model, gate elimination, is inherently limited to proving…

Computational Complexity · Computer Science 2020-12-09 Alexander Golovnev , Alexander S. Kulikov , R. Ryan Williams

We analyze a scheme for quantum computation where quantum gates can be continuously changed from standard dynamic gates to purely geometric ones. These gates are enacted by controlling a set of parameters that are subject to unwanted…

Quantum Physics · Physics 2009-11-10 Shi-Liang Zhu , Paolo Zanardi

Single flux quantum (SFQ) circuits are an attractive beyond-CMOS technology because they promise two orders of magnitude lower power at clock frequencies exceeding 25 GHz.However, every SFQ gate is clocked creating very deep gate-level…

Hardware Architecture · Computer Science 2020-01-30 Souvik Kundu , Gourav datta , Peter A. Beerel , Massoud Pedram

In this paper, we propose a new method to design low-density parity-check Hadamard (LDPC-Hadamard) codes, a type of ultimate-Shannon-limit approaching channel codes. The technique is based on applying Hadamard constraints to the check nodes…

Information Theory · Computer Science 2021-01-06 Peng W. Zhang , Francis C. M. Lau , Chiu-W. Sham

This paper introduces a compact and secure 16-bit substitution box (S-box) designed over the composite field $\F_{(((2^2)^2)^2)^2}$, optimized for both hardware efficiency and cryptographic robustness. The proposed S-box decomposes…

Cryptography and Security · Computer Science 2025-07-03 Bahram Rashidi , Behrooz Khadem

Floquet codes have recently emerged as a new family of error-correcting codes, and have drawn significant interest across both theoretical and practical quantum computing. A central open question has been how to implement logical operations…

Quantum Physics · Physics 2026-01-14 Alexandra E. Moylett , Bhargavi Jonnadula

Inevitable interactions with the reservoir largely degrade the performance of non-local gates, which hinders practical quantum computation from coming into existence. Here we experimentally demonstrate a 99.920(7)\%-fidelity controlled-NOT…

Quantum Physics · Physics 2022-12-07 Tianyu Xie , Zhiyuan Zhao , Shaoyi Xu , Xi Kong , Zhiping Yang , Mengqi Wang , Ya Wang , Fazhan Shi , Jiangfeng Du

We generalize the concept of folding from surface codes to CSS codes by considering certain dualities within them. In particular, this gives a general method to implement logical operations in suitable LDPC quantum codes using transversal…

Quantum Physics · Physics 2024-06-19 Nikolas P. Breuckmann , Simon Burton

We investigate Clifford+$T$ quantum circuits with a small number of $T$-gates. Using the sparsification lemma, we identify time complexity lower bounds in terms of $T$-gate count below which a strong simulator would improve on the…

Quantum Physics · Physics 2019-02-26 Cupjin Huang , Michael Newman , Mario Szegedy

We examine the Art Gallery Problem with Edge Guards. We present a heuristic algorithm to arrange edge guards to guard only the inward side of the walls of any N-vertex simple polygonal gallery using at most roof (N/4) edge guards - a…

Metric Geometry · Mathematics 2012-07-17 R. Nandakumar

Quantum computation based on nonadiabatic geometric phases has attracted a broad range of interests, due to its fast manipulation and inherent noise resistance. However, it is limited to some special evolution paths, and the gate-times are…

Quantum Physics · Physics 2021-11-29 Cheng-Yun Ding , Li-Na Ji , Tao Chen , Zheng-Yuan Xue

Bivariate bicycle codes are promising candidates for high-threshold, low-overhead fault-tolerant quantum memories. Meanwhile, color codes are the most prominent self-dual CSS codes, supporting transversal Clifford gates that have been…

Quantum Physics · Physics 2026-01-13 Zijian Liang , Yu-An Chen

The basic building blocks for Resonant Tunnelling Diode (RTD) logic circuits are Threshold Gates (TGs) instead of the conventional Boolean gates (AND, OR, NAND, NOR) due to the fact that, when designing with RTDs, threshold gates can be…

Other Condensed Matter · Physics 2007-08-15 H. Pettenghi , M. -J. Avedillo , J. -M. Quintana

Surface code based quantum computers show great promise for fault-tolerant quantum computing, but most architectures needlessly increase the spacetime volume of a computation due to qubits sitting idly during a computation. Active volume…

Quantum Physics · Physics 2025-04-29 Sam Heavey

We give three new algorithms for efficient in-place estimation, without using ancilla qubits, of average fidelity of a quantum logic gate acting on a d-dimensional system using much fewer random bits than what was known so far. Previous…

Quantum Physics · Physics 2019-01-23 Aditya Nema , Pranab Sen

An experimental study is combined with numerical modelling to investigate new ways to reduce cross-flow vibrations of hydraulic gates with underflow. A rectangular gate section placed in a flume was given freedom to vibrate in the vertical…

Fluid Dynamics · Physics 2015-06-18 C. D. Erdbrink , V. V. Krzhizhanovskaya , P. M. A. Sloot

In this paper, we give upper bounds on the sizes of $(d, L)$ list-decodable codes in the Hamming metric space from covering codes with the covering radius smaller than or equal to $d$. When the list size $L$ is $1$, this gives many new…

Information Theory · Computer Science 2023-01-25 Hao Chen , Longjiang Qu , Chengju Li , Shanxiang Lyu , Liqing Xu

In this work, we consider biased-noise qubits affected only by bit-flip errors, which is motivated by existing systems of stabilized cat qubits. This property allows us to design a class of noisy Hadamard-tests involving entangling and…

We show that the quantum logic gates, {\it viz.} the single qubit Hadamard and Phase Shift gates, can also be realised using q-deformed angular momentum states constructed via the Jordan-Schwinger mechanism with two q-deformed oscillators.…

Quantum Physics · Physics 2007-05-23 Debashis Gangopadhyay , Mahendra Nath Sinha Roy

Hybrid quantum algorithms combine the strengths of quantum and classical computing. Many quantum algorithms, such as the variational quantum eigensolver (VQE), leverage this synergy. However, quantum circuits are executed in full, even when…

Quantum Physics · Physics 2025-07-09 Yanbin Chen , Christian B. Mendl , Helmut Seidl