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There is no unique way to encode a quantum algorithm into a quantum circuit. With limited qubit counts, connectivity, and coherence times, a quantum circuit optimization is essential to make the best use of near-term quantum devices. We…

We present an efficient protocol leveraging classical computation to support Initial State Preparation for strongly correlated fermionic systems, a critical bottleneck for fault-tolerant quantum simulation. Focusing on nuclear shell model…

Quantum Physics · Physics 2026-03-27 Joe Gibbs , Lukasz Cincio , Chandan Sarma , Zoë Holmes , Paul Stevenson

The overhead cost of performing universal fault-tolerant quantum computation for large scale quantum algorithms is very high. Despite several attempts at alternative schemes, magic state distillation remains one of the most efficient…

Quantum Physics · Physics 2020-10-30 Christopher Chamberland , Kyungjoo Noh

There are various gate sets that can be used to describe a quantum computation. A particularly popular gate set in the literature on quantum computing consists of arbitrary single-qubit gates and 2-qubit CNOT gates. A CNOT gate is however…

Quantum Physics · Physics 2022-09-05 John van de Wetering

Quantum computing potentially offers exponential speed-ups over classical computing for certain tasks. A central, outstanding challenge to making quantum computing practical is to achieve fault tolerance, meaning that computations of any…

Quantum Physics · Physics 2021-02-01 Jacob Hastrup , Kimin Park , Jonatan Bohr Brask , Radim Filip , Ulrik Lund Andersen

Current quantum programming is dominated by low-level, circuit-centric approaches that limit the potential for compiler optimization. This work presents how a high-level programming construct provides compilers with the semantic information…

Quantum Physics · Physics 2025-10-29 Evandro C. R. Rosa , Jerusa Marchi , Eduardo I. Duzzioni , Rafael de Santiago

We present an algorithm utilizing mid-circuit measurement and feedback that prepares Dicke states with polylogarithmically many ancillas and polylogarithmic depth. Our algorithm uses only global mid-circuit projective measurements and…

In order to assess potential advantages of quantum algorithms that require quantum oracles as subroutines, the careful evaluation of the overall complexity of the oracles themselves is crucial. This study examines the quantum routines…

Quantum Physics · Physics 2025-04-29 Sven Danz , Tobias Stollenwerk , Alessandro Ciani

We propose a scheme for an exact efficient transformation of a tensor product state of many identically prepared qubits into a state of a logarithmically small number of qubits. Using a quadratic number of elementary quantum gates we…

Quantum Physics · Physics 2010-03-31 Martin Plesch , Vladimir Buzek

We use a random search technique to find quantum gate sequences that implement perfect quantum state preparation or unitary operator synthesis with arbitrary targets. This approach is based on the recent discovery that there is a large…

Quantum Physics · Physics 2024-10-25 Sahel Ashhab , Fumiki Yoshihara , Miwako Tsuji , Mitsuhisa Sato , Kouichi Semba

This paper presents novel methods for optimizing multi-controlled quantum gates, which naturally arise in high-level quantum programming. Our primary approach involves rewriting $U(2)$ gates as $SU(2)$ gates, utilizing one auxiliary qubit…

Quantum Physics · Physics 2025-03-12 Evandro C. R. Rosa , Eduardo I. Duzzioni , Rafael de Santiago

There is no unique way to encode a quantum algorithm into a quantum circuit. With limited qubit counts, connectivities, and coherence times, circuit optimization is essential to make the best use of near-term quantum devices. We introduce…

How many T gates are needed to approximate an arbitrary $n$-qubit quantum state to within error $\varepsilon$? Improving prior work of Low, Kliuchnikov, and Schaeffer, we show that the optimal asymptotic scaling is…

Quantum Physics · Physics 2025-10-13 David Gosset , Robin Kothari , Kewen Wu

Quantum machine learning (QML) is emerging as an application of quantum computing with the potential to deliver quantum advantage, but its realisation for practical applications remains impeded by challenges. Amongst those, a key barrier is…

In order to demonstrate non-trivial quantum computations experimentally, such as the synthesis of arbitrary entangled states, it will be useful to understand how to decompose a desired quantum computation into the shortest possible sequence…

Quantum Physics · Physics 2009-11-10 Farrokh Vatan , Colin Williams

Robust quantum computation requires encoding delicate quantum information into degrees of freedom that are hard for the environment to change. Quantum encodings have been demonstrated in many physical systems by observing and correcting…

Quantum Physics · Physics 2017-11-08 Maika Takita , Andrew W. Cross , A. D. Córcoles , Jerry M. Chow , Jay M. Gambetta

We introduce a quantum algorithm to efficiently prepare states with a small energy variance at the target energy. We achieve it by filtering a product state at the given energy with a Lorentzian filter of width $\delta$. Given a local…

Quantum Physics · Physics 2024-07-03 Reinis Irmejs , Mari Carmen Bañuls , J. Ignacio Cirac

Parallel computation enables multiple processors to execute different parts of a task simultaneously, improving processing speed and efficiency. In quantum computing, parallel gate implementation involves executing gates independently in…

Quantum Physics · Physics 2024-11-20 Boris Arseniev

Preparing arbitrary logical states is a central primitive for universal fault-tolerant quantum computation and the cost of encoded-state preparation contributes directly to the overall resource overhead. This makes the synthesis of…

Quantum Physics · Physics 2026-05-18 Tom Peham , Matthew Steinberg , Robert Wille , Sascha Heußen

We present a method that outputs a sequence of simple unitary operations to prepare a given quantum state that is a generalized coherent state. Our method takes as inputs the expectation values of some relevant observables on the state to…

Quantum Physics · Physics 2020-01-08 Rolando D. Somma