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Hybrid discrete-continuous compilation of trapped-ion quantum circuits with deep reinforcement learning Quantum (IF 6.4) Pub Date : 2024-05-14 Francesco Preti, Michael Schilling, Sofiene Jerbi, Lea M. Trenkwalder, Hendrik Poulsen Nautrup, Felix Motzoi, Hans J. Briegel
Shortening quantum circuits is crucial to reducing the destructive effect of environmental decoherence and enabling useful algorithms. Here, we demonstrate an improvement in such compilation tasks via a combination of using hybrid discrete-continuous optimization across a continuous gate set, and architecture-tailored implementation. The continuous parameters are discovered with a gradient-based optimization
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CSS code surgery as a universal construction Quantum (IF 6.4) Pub Date : 2024-05-14 Alexander Cowtan, Simon Burton
We define code maps between Calderbank-Shor-Steane (CSS) codes using maps between chain complexes, and describe code surgery between such codes using a specific colimit in the category of chain complexes. As well as describing a surgery operation, this gives a general recipe for new codes. As an application we describe how to `merge' and `split' along a shared $\overline{X}$ or $\overline{Z}$ operator
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Partial Syndrome Measurement for Hypergraph Product Codes Quantum (IF 6.4) Pub Date : 2024-05-14 Noah Berthusen, Daniel Gottesman
Hypergraph product codes are a promising avenue to achieving fault-tolerant quantum computation with constant overhead. When embedding these and other constant-rate qLDPC codes into 2D, a significant number of nonlocal connections are required, posing difficulties for some quantum computing architectures. In this work, we introduce a fault-tolerance scheme that aims to alleviate the effects of implementing
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Virtual mitigation of coherent non-adiabatic transitions by echo verification Quantum (IF 6.4) Pub Date : 2024-05-14 Benjamin F. Schiffer, Dyon van Vreumingen, Jordi Tura, Stefano Polla
Transitions out of the ground space limit the performance of quantum adiabatic algorithms, while hardware imperfections impose stringent limitations on the circuit depth. We propose an adiabatic echo verification protocol which mitigates both coherent and incoherent errors, arising from non-adiabatic transitions and hardware noise, respectively. Quasi-adiabatically evolving forward and backward allows
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Magic in generalized Rokhsar-Kivelson wavefunctions Quantum (IF 6.4) Pub Date : 2024-05-14 Poetri Sonya Tarabunga, Claudio Castelnovo
Magic is a property of a quantum state that characterizes its deviation from a stabilizer state, serving as a useful resource for achieving universal quantum computation e.g., within schemes that use Clifford operations. In this work, we study magic, as quantified by the stabilizer Renyi entropy, in a class of models known as generalized Rokhsar-Kivelson systems, i.e., Hamiltonians that allow a stochastic
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Generating $k$ EPR-pairs from an $n$-party resource state Quantum (IF 6.4) Pub Date : 2024-05-14 Sergey Bravyi, Yash Sharma, Mario Szegedy, Ronald de Wolf
Motivated by quantum network applications over classical channels, we initiate the study of $n$-party resource states from which LOCC protocols can create EPR-pairs between any $k$ disjoint pairs of parties. We give constructions of such states where $k$ is not too far from the optimal $n/2$ while the individual parties need to hold only a constant number of qubits. In the special case when each party
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Kerr-effect-based quantum logical gates in decoherence-free subspace Quantum (IF 6.4) Pub Date : 2024-05-13 Fang-Fang Du, Gang Fan, Xue-Mei Ren
The decoherence effect caused by the coupling between the system and the environment undoubtedly leads to the errors in efficient implementations of two (or three) qubit logical gates in quantum information processing. Fortunately, decoherence-free subspace (DFS) introduced can effectively decrease the influence of decoherence effect. In this paper, we propose some schemes for setting up a family of
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Minimal-noise estimation of noncommuting rotations of a spin Quantum (IF 6.4) Pub Date : 2024-05-08 Jakub Czartowski, Karol Życzkowski, Daniel Braun
We propose an analogue of $\text{SU}(1,1)$ interferometry to measure rotation of a spin by using two-spin squeezed states. Attainability of the Heisenberg limit for the estimation of the rotation angle is demonstrated for maximal squeezing. For a specific direction and strength an advantage in sensitivity for $all$ equatorial rotation axes (and hence non-commuting rotations) over the classical bound
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Tensor network decompositions for absolutely maximally entangled states Quantum (IF 6.4) Pub Date : 2024-05-08 Balázs Pozsgay, Ian M. Wanless
Absolutely maximally entangled (AME) states of $k$ qudits (also known as perfect tensors) are quantum states that have maximal entanglement for all possible bipartitions of the sites/parties. We consider the problem of whether such states can be decomposed into a tensor network with a small number of tensors, such that all physical and all auxiliary spaces have the same dimension $D$. We find that
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Introduction to Haar Measure Tools in Quantum Information: A Beginner’s Tutorial Quantum (IF 6.4) Pub Date : 2024-05-08 Antonio Anna Mele
The Haar measure plays a vital role in quantum information, but its study often requires a deep understanding of representation theory, posing a challenge for beginners. This tutorial aims to provide a basic introduction to Haar measure tools in quantum information, utilizing only basic knowledge of linear algebra and thus aiming to make this topic more accessible. The tutorial begins by introducing
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Relational superposition measurements with a material quantum ruler Quantum (IF 6.4) Pub Date : 2024-05-06 Hui Wang, Flaminia Giacomini, Franco Nori, Miles P. Blencowe
In physics, it is crucial to identify operational measurement procedures to give physical meaning to abstract quantities. There has been significant effort to define time operationally using quantum systems, but the same has not been achieved for space. Developing an operational procedure to obtain information about the location of a quantum system is particularly important for a theory combining general
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Energy conservation and fluctuation theorem are incompatible for quantum work Quantum (IF 6.4) Pub Date : 2024-05-06 Karen V. Hovhannisyan, Alberto Imparato
Characterizing fluctuations of work in coherent quantum systems is notoriously problematic. Here we reveal the ultimate source of the problem by proving that ($\mathfrak{A}$) energy conservation and ($\mathfrak{B}$) the Jarzynski fluctuation theorem cannot be observed at the same time. Condition $\mathfrak{A}$ stipulates that, for any initial state of the system, the measured average work must be equal
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Robust sparse IQP sampling in constant depth Quantum (IF 6.4) Pub Date : 2024-05-06 Louis Paletta, Anthony Leverrier, Alain Sarlette, Mazyar Mirrahimi, Christophe Vuillot
Between NISQ (noisy intermediate scale quantum) approaches without any proof of robust quantum advantage and fully fault-tolerant quantum computation, we propose a scheme to achieve a provable superpolynomial quantum advantage (under some widely accepted complexity conjectures) that is robust to noise with minimal error correction requirements. We choose a class of sampling problems with commuting
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Quantum time dilation in a gravitational field Quantum (IF 6.4) Pub Date : 2024-05-07 Jerzy Paczos, Kacper Dębski, Piotr T. Grochowski, Alexander R. H. Smith, Andrzej Dragan
According to relativity, the reading of an ideal clock is interpreted as the elapsed proper time along its classical trajectory through spacetime. In contrast, quantum theory allows the association of many simultaneous trajectories with a single quantum clock, each weighted appropriately. Here, we investigate how the superposition principle affects the gravitational time dilation observed by a simple
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Characterising the Hierarchy of Multi-time Quantum Processes with Classical Memory Quantum (IF 6.4) Pub Date : 2024-05-02 Philip Taranto, Marco Túlio Quintino, Mio Murao, Simon Milz
Memory is the fundamental form of temporal complexity: when present but uncontrollable, it manifests as non-Markovian noise; conversely, if controllable, memory can be a powerful resource for information processing. Memory effects arise from/are transmitted via interactions between a system and its environment; as such, they can be either classical or quantum. From a practical standpoint, quantum processes
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Entanglement-assisted Quantum Reed-Muller Tensor Product Codes Quantum (IF 6.4) Pub Date : 2024-05-02 Priya J. Nadkarni, Praveen Jayakumar, Arpit Behera, Shayan Srinivasa Garani
We present the construction of standard entanglement-assisted (EA) qubit Reed-Muller (RM) codes and their tensor product variants from classical RM codes. We show that the EA RM codes obtained using the CSS construction have zero coding rate and negative catalytic rate. We further show that EA codes constructed from these same classical RM codes using the tensor product code (TPC) construction have
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Quantum copy-protection of compute-and-compare programs in the quantum random oracle model Quantum (IF 6.4) Pub Date : 2024-05-02 Andrea Coladangelo, Christian Majenz, Alexander Poremba
Copy-protection allows a software distributor to encode a program in such a way that it can be evaluated on any input, yet it cannot be "pirated" – a notion that is impossible to achieve in a classical setting. Aaronson (CCC 2009) initiated the formal study of quantum copy-protection schemes, and speculated that quantum cryptography could offer a solution to the problem thanks to the quantum no-cloning
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A generic quantum Wielandt’s inequality Quantum (IF 6.4) Pub Date : 2024-05-02 Yifan Jia, Angela Capel
Quantum Wielandt's inequality gives an optimal upper bound on the minimal length $k$ such that length-$k$ products of elements in a generating system span $M_n(\mathbb{C})$. It is conjectured that $k$ should be of order $\mathcal{O}(n^2)$ in general. In this paper, we give an overview of how the question has been studied in the literature so far and its relation to a classical question in linear algebra
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Certifying long-range quantum correlations through routed Bell tests Quantum (IF 6.4) Pub Date : 2024-05-02 Edwin Peter Lobo, Jef Pauwels, Stefano Pironio
Losses in the transmission channel, which increase with distance, pose a major obstacle to photonics demonstrations of quantum nonlocality and its applications. Recently, Chaturvedi, Viola, and Pawlowski (CVP) [arXiv:2211.14231] introduced a variation of standard Bell experiments with the goal of extending the range over which quantum nonlocality can be demonstrated. These experiments, which we call
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Custom Bell inequalities from formal sums of squares Quantum (IF 6.4) Pub Date : 2024-05-02 Victor Barizien, Pavel Sekatski, Jean-Daniel Bancal
Bell inequalities play a key role in certifying quantum properties for device-independent quantum information protocols. It is still a major challenge, however, to devise Bell inequalities tailored for an arbitrary given quantum state. Existing approaches based on sums of squares provide results in this direction, but they are restricted by the necessity of first choosing measurement settings suited
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Check-Agnosia based Post-Processor for Message-Passing Decoding of Quantum LDPC Codes Quantum (IF 6.4) Pub Date : 2024-05-02 Julien du Crest, Francisco Garcia-Herrero, Mehdi Mhalla, Valentin Savin, Javier Valls
The inherent degeneracy of quantum low-density parity-check codes poses a challenge to their decoding, as it significantly degrades the error-correction performance of classical message-passing decoders. To improve their performance, a post-processing algorithm is usually employed. To narrow the gap between algorithmic solutions and hardware limitations, we introduce a new post-processing algorithm
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Resource analysis for quantum-aided Byzantine agreement with the four-qubit singlet state Quantum (IF 6.4) Pub Date : 2024-04-30 Zoltán Guba, István Finta, Ákos Budai, Lóránt Farkas, Zoltán Zimborás, András Pályi
In distributed computing, a Byzantine fault is a condition where a component behaves inconsistently, showing different symptoms to different components of the system. Consensus among the correct components can be reached by appropriately crafted communication protocols even in the presence of byzantine faults. Quantum-aided protocols built upon distributed entangled quantum states are worth considering
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Complexity of Supersymmetric Systems and the Cohomology Problem Quantum (IF 6.4) Pub Date : 2024-04-30 Chris Cade, P. Marcos Crichigno
We consider the complexity of the local Hamiltonian problem in the context of fermionic Hamiltonians with $\mathcal N=2 $ supersymmetry and show that the problem remains $\mathsf{QMA}$-complete. Our main motivation for studying this is the well-known fact that the ground state energy of a supersymmetric system is exactly zero if and only if a certain cohomology group is nontrivial. This opens the door
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Metrology and multipartite entanglement in measurement-induced phase transition Quantum (IF 6.4) Pub Date : 2024-04-30 Giovanni Di Fresco, Bernardo Spagnolo, Davide Valenti, Angelo Carollo
Measurement-induced phase transition arises from the competition between a deterministic quantum evolution and a repeated measurement process. We explore the measurement-induced phase transition through the Quantum Fisher Information in two different metrological scenarios. We demonstrate through the scaling behavior of the quantum Fisher information the transition of the multi-partite entanglement
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Low-depth simulations of fermionic systems on square-grid quantum hardware Quantum (IF 6.4) Pub Date : 2024-04-30 Manuel G. Algaba, P. V. Sriluckshmy, Martin Leib, Fedor Šimkovic IV
We present a general strategy for mapping fermionic systems to quantum hardware with square qubit connectivity which yields low-depth quantum circuits, counted in the number of native two-qubit fSIM gates. We achieve this by leveraging novel operator decomposition and circuit compression techniques paired with specifically chosen low-depth fermion-to-qubit mappings and allow for a high degree of gate
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Photonic entanglement with accelerated light Quantum (IF 6.4) Pub Date : 2024-04-30 R. C. Souza Pimenta, G. H. dos Santos, A. B. Barreto, L. C. Celeri, P. H. Souto Ribeiro
Accelerated light has been demonstrated with laser light and diffraction. Within the diffracting field it is possible to identify a portion that carries most of the beam energy, which propagates in a curved trajectory as it would have been accelerated by a gravitational field for instance. Here, we analyze the effects of this kind of acceleration over the entanglement between twin beams produced in
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Mutually unbiased bases: polynomial optimization and symmetry Quantum (IF 6.4) Pub Date : 2024-04-30 Sander Gribling, Sven Polak
A set of $k$ orthonormal bases of $\mathbb C^d$ is called mutually unbiased if $|\langle e,f\rangle |^2 = 1/d$ whenever $e$ and $f$ are basis vectors in distinct bases. A natural question is for which pairs $(d,k)$ there exist $k$ mutually unbiased bases in dimension $d$. The (well-known) upper bound $k \leq d+1$ is attained when $d$ is a power of a prime. For all other dimensions it is an open problem
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Learning quantum many-body systems from a few copies Quantum (IF 6.4) Pub Date : 2024-04-30 Cambyse Rouzé, Daniel Stilck França
Estimating physical properties of quantum states from measurements is one of the most fundamental tasks in quantum science. In this work, we identify conditions on states under which it is possible to infer the expectation values of all quasi-local observables of a state from a number of copies that scales polylogarithmically with the system's size and polynomially on the locality of the target observables
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Approximating quantum channels by completely positive maps with small Kraus rank Quantum (IF 6.4) Pub Date : 2024-04-30 Cécilia Lancien, Andreas Winter
We study the problem of approximating a quantum channel by one with as few Kraus operators as possible (in the sense that, for any input state, the output states of the two channels should be close to one another). Our main result is that any quantum channel mapping states on some input Hilbert space $\mathrm{A}$ to states on some output Hilbert space $\mathrm{B}$ can be compressed into one with order
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A family of permutationally invariant quantum codes Quantum (IF 6.4) Pub Date : 2024-04-30 Arda Aydin, Max A. Alekseyev, Alexander Barg
We construct a new family of permutationally invariant codes that correct $t$ Pauli errors for any $t\ge 1$. We also show that codes in the new family correct quantum deletion errors as well as spontaneous decay errors. Our construction contains some of the previously known permutationally invariant quantum codes as particular cases, which also admit transversal gates. In many cases, the codes in the
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Derivative Pricing using Quantum Signal Processing Quantum (IF 6.4) Pub Date : 2024-04-30 Nikitas Stamatopoulos, William J. Zeng
Pricing financial derivatives on quantum computers typically includes quantum arithmetic components which contribute heavily to the quantum resources required by the corresponding circuits. In this manuscript, we introduce a method based on Quantum Signal Processing (QSP) to encode financial derivative payoffs directly into quantum amplitudes, alleviating the quantum circuits from the burden of costly
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Hidden variable model for quantum computation with magic states on qudits of any dimension Quantum (IF 6.4) Pub Date : 2024-04-30 Michael Zurel, Cihan Okay, Robert Raussendorf, Arne Heimendahl
It was recently shown that a hidden variable model can be constructed for universal quantum computation with magic states on qubits. Here we show that this result can be extended, and a hidden variable model can be defined for quantum computation with magic states on qudits with any Hilbert space dimension. This model leads to a classical simulation algorithm for universal quantum computation.
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Improved Quantum Query Complexity on Easier Inputs Quantum (IF 6.4) Pub Date : 2024-04-08 Noel T. Anderson, Jay-U Chung, Shelby Kimmel, Da-Yeon Koh, Xiaohan Ye
Quantum span program algorithms for function evaluation sometimes have reduced query complexity when promised that the input has a certain structure. We design a modified span program algorithm to show these improvements persist even without a promise ahead of time, and we extend this approach to the more general problem of state conversion. As an application, we prove exponential and superpolynomial
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Inplace Access to the Surface Code Y Basis Quantum (IF 6.4) Pub Date : 2024-04-08 Craig Gidney
In this paper, I cut the cost of Y basis measurement and initialization in the surface code by nearly an order of magnitude. Fusing twist defects diagonally across the surface code patch reaches the Y basis in $\lfloor d/2 \rfloor + 2$ rounds, without leaving the bounding box of the patch and without reducing the code distance. I use Monte Carlo sampling to benchmark the performance of the construction
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Efficient solution of the non-unitary time-dependent Schrodinger equation on a quantum computer with complex absorbing potential Quantum (IF 6.4) Pub Date : 2024-04-08 Mariane Mangin-Brinet, Jing Zhang, Denis Lacroix, Edgar Andres Ruiz Guzman
We explore the possibility of adding complex absorbing potential at the boundaries when solving the one-dimensional real-time Schrödinger evolution on a grid using a quantum computer with a fully quantum algorithm described on a $n$ qubit register. Due to the complex potential, the evolution mixes real- and imaginary-time propagation and the wave function can potentially be continuously absorbed during
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Quantum advantage in temporally flat measurement-based quantum computation Quantum (IF 6.4) Pub Date : 2024-04-09 Michael de Oliveira, Luís S. Barbosa, Ernesto F. Galvão
Several classes of quantum circuits have been shown to provide a quantum computational advantage under certain assumptions. The study of ever more restricted classes of quantum circuits capable of quantum advantage is motivated by possible simplifications in experimental demonstrations. In this paper we study the efficiency of measurement-based quantum computation with a completely flat temporal ordering
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Optimizing Variational Quantum Algorithms with qBang: Efficiently Interweaving Metric and Momentum to Navigate Flat Energy Landscapes Quantum (IF 6.4) Pub Date : 2024-04-09 David Fitzek, Robert S. Jonsson, Werner Dobrautz, Christian Schäfer
Variational quantum algorithms (VQAs) represent a promising approach to utilizing current quantum computing infrastructures. VQAs are based on a parameterized quantum circuit optimized in a closed loop via a classical algorithm. This hybrid approach reduces the quantum processing unit load but comes at the cost of a classical optimization that can feature a flat energy landscape. Existing optimization
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Efficient Computation of the Quantum Rate-Distortion Function Quantum (IF 6.4) Pub Date : 2024-04-09 Kerry He, James Saunderson, Hamza Fawzi
The quantum rate-distortion function plays a fundamental role in quantum information theory, however there is currently no practical algorithm which can efficiently compute this function to high accuracy for moderate channel dimensions. In this paper, we show how symmetry reduction can significantly simplify common instances of the entanglement-assisted quantum rate-distortion problems. This allows
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Classical analogue of quantum superdense coding and communication advantage of a single quantum system Quantum (IF 6.4) Pub Date : 2024-04-09 Ram Krishna Patra, Sahil Gopalkrishna Naik, Edwin Peter Lobo, Samrat Sen, Tamal Guha, Some Sankar Bhattacharya, Mir Alimuddin, Manik Banik
We analyze utility of communication channels in absence of any short of quantum or classical correlation shared between the sender and the receiver. To this aim, we propose a class of two-party communication games, and show that the games cannot be won given a noiseless $1$-bit classical channel from the sender to the receiver. Interestingly, the goal can be perfectly achieved if the channel is assisted
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Double-bracket quantum algorithms for diagonalization Quantum (IF 6.4) Pub Date : 2024-04-09 Marek Gluza
This work proposes double-bracket iterations as a framework for obtaining diagonalizing quantum circuits. Their implementation on a quantum computer consists of interlacing evolutions generated by the input Hamiltonian with diagonal evolutions which can be chosen variationally. No qubit overheads or controlled-unitary operations are needed but the method is recursive which makes the circuit depth grow
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From Non-Markovian Dissipation to Spatiotemporal Control of Quantum Nanodevices Quantum (IF 6.4) Pub Date : 2024-04-03 Thibaut Lacroix, Brendon W. Lovett, Alex W. Chin
Nanodevices exploiting quantum effects are critically important elements of future quantum technologies (QT), but their real-world performance is strongly limited by decoherence arising from local `environmental' interactions. Compounding this, as devices become more complex, i.e. contain multiple functional units, the `local' environments begin to overlap, creating the possibility of environmentally
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Quantum Monte Carlo simulations for financial risk analytics: scenario generation for equity, rate, and credit risk factors Quantum (IF 6.4) Pub Date : 2024-04-04 Titos Matsakos, Stuart Nield
Monte Carlo (MC) simulations are widely used in financial risk management, from estimating value-at-risk (VaR) to pricing over-the-counter derivatives. However, they come at a significant computational cost due to the number of scenarios required for convergence. If a probability distribution is available, Quantum Amplitude Estimation (QAE) algorithms can provide a quadratic speed-up in measuring its
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The qudit Pauli group: non-commuting pairs, non-commuting sets, and structure theorems Quantum (IF 6.4) Pub Date : 2024-04-04 Rahul Sarkar, Theodore J. Yoder
Qudits with local dimension $d \gt 2$ can have unique structure and uses that qubits ($d=2$) cannot. Qudit Pauli operators provide a very useful basis of the space of qudit states and operators. We study the structure of the qudit Pauli group for any, including composite, $d$ in several ways. To cover composite values of $d$, we work with modules over commutative rings, which generalize the notion
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Two-Particle Scattering on Non-Translation Invariant Line Lattices Quantum (IF 6.4) Pub Date : 2024-04-04 Luna Lima e Silva, Daniel Jost Brod
Quantum walks have been used to develop quantum algorithms since their inception, and can be seen as an alternative to the usual circuit model; combining single-particle quantum walks on sparse graphs with two-particle scattering on a line lattice is sufficient to perform universal quantum computation. In this work we solve the problem of two-particle scattering on the line lattice for a family of
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Heisenberg-limited metrology with perturbing interactions Quantum (IF 6.4) Pub Date : 2024-03-28 Chao Yin, Andrew Lucas
We show that it is possible to perform Heisenberg-limited metrology on GHZ-like states, in the presence of generic spatially local, possibly strong interactions during the measurement process. An explicit protocol, which relies on single-qubit measurements and feedback based on polynomial-time classical computation, achieves the Heisenberg limit. In one dimension, matrix product state methods can be
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Enriched string-net models and their excitations Quantum (IF 6.4) Pub Date : 2024-03-28 David Green, Peter Huston, Kyle Kawagoe, David Penneys, Anup Poudel, Sean Sanford
Boundaries of Walker-Wang models have been used to construct commuting projector models which realize chiral unitary modular tensor categories (UMTCs) as boundary excitations. Given a UMTC $\mathcal{A}$ representing the Witt class of an anomaly, the article [10] gave a commuting projector model associated to an $\mathcal{A}$-enriched unitary fusion category $\mathcal{X}$ on a 2D boundary of the 3D
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Loss-tolerant architecture for quantum computing with quantum emitters Quantum (IF 6.4) Pub Date : 2024-03-28 Matthias C. Löbl, Stefano Paesani, Anders S. Sørensen
We develop an architecture for measurement-based quantum computing using photonic quantum emitters. The architecture exploits spin-photon entanglement as resource states and standard Bell measurements of photons for fusing them into a large spin-qubit cluster state. The scheme is tailored to emitters with limited memory capabilities since it only uses an initial non-adaptive (ballistic) fusion process
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Randomized measurement protocols for lattice gauge theories Quantum (IF 6.4) Pub Date : 2024-03-27 Jacob Bringewatt, Jonathan Kunjummen, Niklas Mueller
Randomized measurement protocols, including classical shadows, entanglement tomography, and randomized benchmarking are powerful techniques to estimate observables, perform state tomography, or extract the entanglement properties of quantum states. While unraveling the intricate structure of quantum states is generally difficult and resource-intensive, quantum systems in nature are often tightly constrained
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Effective versus Floquet theory for the Kerr parametric oscillator Quantum (IF 6.4) Pub Date : 2024-03-25 Ignacio García-Mata, Rodrigo G. Cortiñas, Xu Xiao, Jorge Chávez-Carlos, Victor S. Batista, Lea F. Santos, Diego A. Wisniacki
Parametric gates and processes engineered from the perspective of the static effective Hamiltonian of a driven system are central to quantum technology. However, the perturbative expansions used to derive static effective models may not be able to efficiently capture all the relevant physics of the original system. In this work, we investigate the conditions for the validity of the usual low-order
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Efficient quantum amplitude encoding of polynomial functions Quantum (IF 6.4) Pub Date : 2024-03-21 Javier Gonzalez-Conde, Thomas W. Watts, Pablo Rodriguez-Grasa, Mikel Sanz
Loading functions into quantum computers represents an essential step in several quantum algorithms, such as quantum partial differential equation solvers. Therefore, the inefficiency of this process leads to a major bottleneck for the application of these algorithms. Here, we present and compare two efficient methods for the amplitude encoding of real polynomial functions on $n$ qubits. This case
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Sequential hypothesis testing for continuously-monitored quantum systems Quantum (IF 6.4) Pub Date : 2024-03-20 Giulio Gasbarri, Matias Bilkis, Elisabet Roda-Salichs, John Calsamiglia
We consider a quantum system that is being continuously monitored, giving rise to a measurement signal. From such a stream of data, information needs to be inferred about the underlying system's dynamics. Here we focus on hypothesis testing problems and put forward the usage of sequential strategies where the signal is analyzed in real time, allowing the experiment to be concluded as soon as the underlying
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Entanglement catalysis for quantum states and noisy channels Quantum (IF 6.4) Pub Date : 2024-03-20 Chandan Datta, Tulja Varun Kondra, Marek Miller, Alexander Streltsov
Many applications of the emerging quantum technologies, such as quantum teleportation and quantum key distribution, require singlets, maximally entangled states of two quantum bits. It is thus of utmost importance to develop optimal procedures for establishing singlets between remote parties. As has been shown very recently, singlets can be obtained from other quantum states by using a quantum catalyst
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Dissipation as a resource for Quantum Reservoir Computing Quantum (IF 6.4) Pub Date : 2024-03-20 Antonio Sannia, Rodrigo Martínez-Peña, Miguel C. Soriano, Gian Luca Giorgi, Roberta Zambrini
Dissipation induced by interactions with an external environment typically hinders the performance of quantum computation, but in some cases can be turned out as a useful resource. We show the potential enhancement induced by dissipation in the field of quantum reservoir computing introducing tunable local losses in spin network models. Our approach based on continuous dissipation is able not only
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Constant-sized self-tests for maximally entangled states and single projective measurements Quantum (IF 6.4) Pub Date : 2024-03-21 Jurij Volčič
Self-testing is a powerful certification of quantum systems relying on measured, classical statistics. This paper considers self-testing in bipartite Bell scenarios with small number of inputs and outputs, but with quantum states and measurements of arbitrarily large dimension. The contributions are twofold. Firstly, it is shown that every maximally entangled state can be self-tested with four binary
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Classical shadows based on locally-entangled measurements Quantum (IF 6.4) Pub Date : 2024-03-21 Matteo Ippoliti
We study classical shadows protocols based on randomized measurements in $n$-qubit entangled bases, generalizing the random Pauli measurement protocol ($n = 1$). We show that entangled measurements ($n\geq 2$) enable nontrivial and potentially advantageous trade-offs in the sample complexity of learning Pauli expectation values. This is sharply illustrated by shadows based on two-qubit Bell measurements:
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Beyond-adiabatic Quantum Admittance of a Semiconductor Quantum Dot at High Frequencies: Rethinking Reflectometry as Polaron Dynamics Quantum (IF 6.4) Pub Date : 2024-03-21 L. Peri, G. A. Oakes, L. Cochrane, C. J. B. Ford, M. F. Gonzalez-Zalba
Semiconductor quantum dots operated dynamically are the basis of many quantum technologies such as quantum sensors and computers. Hence, modelling their electrical properties at microwave frequencies becomes essential to simulate their performance in larger electronic circuits. Here, we develop a self-consistent quantum master equation formalism to obtain the admittance of a quantum dot tunnel-coupled
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Transformations in quantum networks via local operations assisted by finitely many rounds of classical communication Quantum (IF 6.4) Pub Date : 2024-03-14 Cornelia Spee, Tristan Kraft
Recent advances have led towards first prototypes of quantum networks in which entanglement is distributed by sources producing bipartite entangled states. This raises the question of which states can be generated in quantum networks based on bipartite sources using local operations and classical communication. In this work, we study state transformations under finite rounds of local operations and
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Can Error Mitigation Improve Trainability of Noisy Variational Quantum Algorithms? Quantum (IF 6.4) Pub Date : 2024-03-14 Samson Wang, Piotr Czarnik, Andrew Arrasmith, M. Cerezo, Lukasz Cincio, Patrick J. Coles
Variational Quantum Algorithms (VQAs) are often viewed as the best hope for near-term quantum advantage. However, recent studies have shown that noise can severely limit the trainability of VQAs, e.g., by exponentially flattening the cost landscape and suppressing the magnitudes of cost gradients. Error Mitigation (EM) shows promise in reducing the impact of noise on near-term devices. Thus, it is
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Teleportation of Post-Selected Quantum States Quantum (IF 6.4) Pub Date : 2024-03-14 Daniel Collins
Teleportation allows Alice to send a pre-prepared quantum state to Bob using only pre-shared entanglement and classical communication. Here we show that it is possible to teleport a state which is also $\it{post}$-selected. Post-selection of a state $\Phi$ means that after Alice has finished her experiment she performs a measurement and only keeps runs of the experiment where the measurement outcome
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Compiling Quantum Circuits for Dynamically Field-Programmable Neutral Atoms Array Processors Quantum (IF 6.4) Pub Date : 2024-03-14 Daniel Bochen Tan, Dolev Bluvstein, Mikhail D. Lukin, Jason Cong
Dynamically field-programmable qubit arrays (DPQA) have recently emerged as a promising platform for quantum information processing. In DPQA, atomic qubits are selectively loaded into arrays of optical traps that can be reconfigured during the computation itself. Leveraging qubit transport and parallel, entangling quantum operations, different pairs of qubits, even those initially far away, can be