IA Scholar Query: Permutational quantum computing.
https://scholar.archive.org/
Internet Archive Scholar query results feedeninfo@archive.orgSat, 31 Dec 2022 00:00:00 GMTfatcat-scholarhttps://scholar.archive.org/help1440Computing Graph Neural Networks: A Survey from Algorithms to Accelerators
https://scholar.archive.org/work/7uww2lnxrbdpnnyvzsanojgnba
Graph Neural Networks (GNNs) have exploded onto the machine learning scene in recent years owing to their capability to model and learn from graph-structured data. Such an ability has strong implications in a wide variety of fields whose data are inherently relational, for which conventional neural networks do not perform well. Indeed, as recent reviews can attest, research in the area of GNNs has grown rapidly and has lead to the development of a variety of GNN algorithm variants as well as to the exploration of ground-breaking applications in chemistry, neurology, electronics, or communication networks, among others. At the current stage research, however, the efficient processing of GNNs is still an open challenge for several reasons. Besides of their novelty, GNNs are hard to compute due to their dependence on the input graph, their combination of dense and very sparse operations, or the need to scale to huge graphs in some applications. In this context, this article aims to make two main contributions. On the one hand, a review of the field of GNNs is presented from the perspective of computing. This includes a brief tutorial on the GNN fundamentals, an overview of the evolution of the field in the last decade, and a summary of operations carried out in the multiple phases of different GNN algorithm variants. On the other hand, an in-depth analysis of current software and hardware acceleration schemes is provided, from which a hardware-software, graph-aware, and communication-centric vision for GNN accelerators is distilled.Sergi Abadal, Akshay Jain, Robert Guirado, Jorge López-Alonso, Eduard Alarcónwork_7uww2lnxrbdpnnyvzsanojgnbaSat, 31 Dec 2022 00:00:00 GMTA Representation-Theoretic Approach to qq-Characters
https://scholar.archive.org/work/6xejk5wplbcczcf2dfza6omcsm
We raise the question of whether (a slightly generalized notion of) qq-characters can be constructed purely representation-theoretically. In the main example of the quantum toroidal gl 1 algebra, geometric engineering of adjoint matter produces an explicit vertex operator RR which computes certain qq-characters, namely Hirzebruch χ y -genera, completely analogously to how the R-matrix R computes q-characters. We give a geometric proof of the independence of preferred direction for the refined vertex in this and more general non-toric settings.Henry Liu, University of Oxford, UKwork_6xejk5wplbcczcf2dfza6omcsmThu, 24 Nov 2022 00:00:00 GMTBackground Independence and Quantum Causal Structure
https://scholar.archive.org/work/rqcdy7axjfc5xclnprtl6motpe
One of the key ways in which quantum mechanics differs from relativity is that it requires a fixed background reference frame for spacetime. In fact, this appears to be one of the main conceptual obstacles to uniting the two theories. Additionally, a combination of the two theories is expected to yield non-classical, or "indefinite", causal structures. In this paper, we present a background-independent formulation of the process matrix formalism - a form of quantum mechanics that allows for indefinite causal structure - while retaining operationally well-defined measurement statistics. We do this by postulating an arbitrary probability distribution of measurement outcomes across discrete "chunks" of spacetime, which we think of as physical laboratories, and then requiring that this distribution be invariant under any permutation of laboratories. We find (a) that one still obtains nontrivial, indefinite causal structures with background independence, (b) that we lose the idea of local operations in distinct laboratories, but can recover it by encoding a reference frame into the physical states of our system, and (c) that permutation invariance imposes surprising symmetry constraints that, although formally similar to a superselection rule, cannot be interpreted as such.Lachlan Parker, Fabio Costawork_rqcdy7axjfc5xclnprtl6motpeWed, 23 Nov 2022 00:00:00 GMTTesting Heisenberg's measurement uncertainty relation of three observables
https://scholar.archive.org/work/2yy5t5jzh5btfks7n76iovfkdq
Heisenberg's measurement uncertainty relations (MUR) of two quantum observables are essential for contemporary researches in quantum foundations and quantum information science. Going beyond, here we report the first experimental test of MURs for three quantum observables. Following the proposal of Bush, Lahti, and Werner [Phys. Rev. A 89, 012129 (2014)], we first establish rigorously MURs for triplets of unbiased qubit observables as combined approximation errors lower-bounded by an incompatibility measure. We then develop a convex programming protocol to numerically find the exact value of the incompatibility measure and the corresponding optimal measurements. Furthermore, we propose a novel implementation of optimal joint measurements and experimentally test our MURs using a single-photon qubit. Lastly, we discuss to analytically calculate the exact value of incompatibility measure for some symmetric triplets. We anticipate that this work may stimulate broad interests associated with the Heisenberg's uncertainty relation of multiple observables, enriching our understanding of quantum mechanics and inspiring innovative applications in quantum information science.Ya-Li Mao, Hu Chen, Chang Niu, Zheng-Da Li, Sixia Yu, Jingyun Fanwork_2yy5t5jzh5btfks7n76iovfkdqWed, 23 Nov 2022 00:00:00 GMTIIB matrix model, bosonic master field, and emergent spacetime
https://scholar.archive.org/work/g5ep65zacjaglphebbnubn637i
The IIB matrix model has been suggested as a particular formulation of nonperturbative superstring theory (M-theory). It has now been realized that an emerging classical spacetime may reside in its large-master field. This bosonic master field can, in principle, give rise to Minkowski and Robertson-Walker spacetimes. The outstanding task is to solve the bosonic master-field equation, which is essentially an algebraic equation. In this article, we present new results for the ( , ) = (10, 4) bosonic master-field equation of the IIB matrix model, where is the number of bosonic matrices and the matrix size. We also give, in a self-contained appendix, explicit results for critical points of the effective bosonic action. The main physics application of the (dimensionless) IIB matrix model may be in providing a (conformal) phase that replaces the Friedmann big bang singularity.Frans R. Klinkhamerwork_g5ep65zacjaglphebbnubn637iWed, 23 Nov 2022 00:00:00 GMTMeasurement uncertainty relation for three observables
https://scholar.archive.org/work/tjvamvw4g5dttevbvsheagwjlu
In this work we establish rigorously a measurement uncertainty relation (MUR) for three unbiased qubit observables, which was previously shown to hold true under some presumptions. The triplet MUR states that the uncertainty, which is quantified by the total statistic distance between the target observables and the jointly implemented observables, is lower bounded by an incompatibility measure that reflects the joint measurement conditions. We derive a necessary and sufficient condition for the triplet MUR to be saturated and the corresponding optimal measurement. To facilitate experimental tests of MURs we propose a straightforward implementation of the optimal joint measurements. The exact values of incompatibility measure are analytically calculated for some symmetric triplets when the corresponding triplet MURs are not saturated. We anticipate that our work may enrich the understanding of quantum incompatibility in terms of MURs and inspire further applications in quantum information science. This work presents a complete theory relevant to a parallel work [Y.-L. Mao, et al., Testing Heisenberg's measurement uncertainty relation of three observables, arXiv:2211.09389] on experimental tests.Sixia Yu, Ya-Li Mao, Chang Niu, Hu Chen, Zheng-Da Li, Jingyun Fanwork_tjvamvw4g5dttevbvsheagwjluWed, 23 Nov 2022 00:00:00 GMTBenchmarking variational quantum circuits with permutation symmetry
https://scholar.archive.org/work/l5hztbgwljaibcx7sjeidls6ku
We propose SnCQA, a set of hardware-efficient variational circuits of equivariant quantum convolutional circuits respective to permutation symmetries and spatial lattice symmetries with the number of qubits n. By exploiting permutation symmetries of the system, such as lattice Hamiltonians common to many quantum many-body and quantum chemistry problems, Our quantum neural networks are suitable for solving machine learning problems where permutation symmetries are present, which could lead to significant savings of computational costs. Aside from its theoretical novelty, we find our simulations perform well in practical instances of learning ground states in quantum computational chemistry, where we could achieve comparable performances to traditional methods with few tens of parameters. Compared to other traditional variational quantum circuits, such as the pure hardware-efficient ansatz (pHEA), we show that SnCQA is more scalable, accurate, and noise resilient (with 20× better performance on 3 × 4 square lattice and 200% - 1000% resource savings in various lattice sizes and key criterions such as the number of layers, parameters, and times to converge in our cases), suggesting a potentially favorable experiment on near-time quantum devices.Han Zheng, Gokul Subramanian Ravi, Hanrui Wang, Kanav Setia, Frederic T. Chong, Junyu Liuwork_l5hztbgwljaibcx7sjeidls6kuWed, 23 Nov 2022 00:00:00 GMTPerfect state transfer in quantum walks on orientable maps
https://scholar.archive.org/work/btvdpcisyzfb3bd26kll6vvaja
A discrete-time quantum walk is the quantum analogue of a Markov chain on a graph. Zhan [J. Algebraic Combin. 53(4):1187-1213, 2020] proposes a model of discrete-time quantum walk whose transition matrix is given by two reflections, using the face and vertex incidence relations of a graph embedded in an orientable surface. We show that the evolution of a general discrete-time quantum walk that consists of two reflections satisfies a Chebyshev recurrence, under a projection. For the vertex-face walk, we prove theorems about perfect state transfer and periodicity and give infinite families of examples where these occur. We bring together tools from algebraic and topological graph theory to analyze the evolution of this walk.Krystal Guo, Vincent Schmeitswork_btvdpcisyzfb3bd26kll6vvajaWed, 23 Nov 2022 00:00:00 GMTDisorder-enhanced nonlinear topological phenomena
https://scholar.archive.org/work/3j7gmohsyrb75kcocgtkk2wzg4
The topology of complex networks plays a fundamental role in understanding phenomena from the collective behavior of spins, neural networks, and power grids to the spread of diseases. Topological phenomena have recently been exploited to preserve the response of systems in the presence of disorder. We propose and demonstrate topological structurally disordered systems with a modal structure that enhances nonlinear phenomena by inhibiting the ultrafast leakage of energy from topological edge modes to bulk modes in the presence of non-linearities. We present the construction of the graph and show that its dynamics enhances the photon pair generation rate by an order of magnitude. Disordered nonlinear topological graphs will enable advanced quantum interconnects, efficient nonlinear sources, and light-based information processing for artificial intelligence.Zhetao Jia, Matteo Seclì, Alexander Avdoshkin, Walid Redjem, Elizabeth Dresselhaus, Joel Moore, Boubacar Kantéwork_3j7gmohsyrb75kcocgtkk2wzg4Wed, 23 Nov 2022 00:00:00 GMTFrequency Measurement with Superradiant Pulses of Incoherently Pumped Calcium Atoms: Role of Quantum Measurement Backaction
https://scholar.archive.org/work/6onorjbec5ge3mpktrqyhhqlk4
A recent experiment demonstrated heterodyne detection-based frequency measurements with superradiant pulses from coherently pumped strontium atoms in an optical lattice clock system, while another experiment has analyzed the statistics of superradiant pulses from incoherently pumped calcium atoms in a similar system. In this article, we propose to perform heterodyne detection of the superradiant pulses from the calcium atoms, and analyze theoretically the corresponding atomic ensemble dynamics in terms of the rotation of a collective spin vector and the incoherent quantum jumps among superradiant Dicke states. We examine the effect of quantum measurement backaction on the emitted field and the collective spin vector dynamics, and we demonstrate that it plays an essential role in the modelling of the frequency measurements. We develop a stochastic mean field theory, which is also applicable to model frequency measurements with steady-state superradiance signals, and to explore quantum measurement effects in the dynamics of atomic ensembles.Huihui Yu, Yuan Zhang, Qilong Wu, Chongxin Shan, Klaus Mølmerwork_6onorjbec5ge3mpktrqyhhqlk4Wed, 23 Nov 2022 00:00:00 GMTQuantum-Classical Tradeoffs in the Random Oracle Model
https://scholar.archive.org/work/sp3inx2tgrfrjheizommsdtcby
We study tradeoffs between quantum and classical queries for hybrid algorithms that have black-box access to a random oracle. Although there are several established techniques for proving query lower bounds for both quantum and classical algorithms, there is no such widely applicable technique for hybrid algorithms and the optimal tradeoffs for many fundamental problems are still unknown x2013 an optimal tradeoff for the search problem was only shown recently by Rosmanis, although not in the random oracle model. For another fundamental problem, collision finding, the optimal tradeoff was not known. In this work, we develop a framework for recording a query transcript for quantum-classical algorithms that represents the knowledge gained by the algorithm. The main feature of this framework is to allow us to record queries in two incompatible bases x2013 classical queries in the standard basis and quantum queries in the Fourier basis x2013 in a consistent way. We call the framework the hybrid compressed oracle as it naturally interpolates between the classical way of recording queries and the compressed oracle framework of Zhandry for recording quantum queries. We demonstrate its applicability by giving a simpler proof of the optimal quantum-classical tradeoff for search and by showing an optimal tradeoff for collision finding.Yassine Hamoudi, Qipeng Liu, Makrand Sinhawork_sp3inx2tgrfrjheizommsdtcbyWed, 23 Nov 2022 00:00:00 GMTQuantum cohomology of Grassmannian and unitary Dyson Brownian motion
https://scholar.archive.org/work/keq65xf4gne3hmxkfvc665q5ji
We study a class of commuting Markov kernels whose simplest element describes the movement of k particles on a discrete circle of size n conditioned to not intersect each other. Such Markov kernels are related to the quantum cohomology ring of Grassmannian, which is an algebraic object counting analytic maps from ℙ^1(ℂ) to the Grassmannian space of k-dimensional vector subspaces of ℂ^n with prescribed constraints at some points of ℙ^1(ℂ). We obtain a Berry-Esseen theorem and a local limit theorem for an arbitrary product of approximately n^2 Markov kernels belonging to the above class, when k is fixed. As a byproduct of those results, we derive asymptotic formulas for the quantum cohomology ring of the Grassmannian in terms of the heat kernel on SU (k).Jérémie Guilhot, Cédric Lecouvey, Pierre Tarragowork_keq65xf4gne3hmxkfvc665q5jiWed, 23 Nov 2022 00:00:00 GMTStructure Constants in 𝒩 = 4 SYM and Separation of Variables
https://scholar.archive.org/work/tsm6duyi2vclnhhjywpvemuhdq
We propose a new framework for computing three-point functions in planar 𝒩=4 super Yang-Mills where these correlators take the form of multiple integrals of Separation of Variables type. We test this formalism at weak coupling at leading and next-to-leading orders in a non-compact SL(2) sector of the theory and all the way to next-to-next-to-leading orders for a compact SU(2) sector. We find evidence that wrapping effects can also be incorporated.Carlos Bercini, Alexandre Homrich, Pedro Vieirawork_tsm6duyi2vclnhhjywpvemuhdqWed, 23 Nov 2022 00:00:00 GMTTime-reversibility and integrability of p:-q resonant vector fields
https://scholar.archive.org/work/xxivy3fv5jhy5bvp6delblxmmm
We study local analytical integrability in a neighborhood of p:-q resonant singular point of a two-dimensional vector field and its connection to time-reversibility with respect to the non-smooth involution φ(x,y)=(y^p/q,x^q/p). Some generalizations of the theory developed by K. S. Sibirsky for 1:-1 resonant case to the p:-q resonant case are presented.Jaume Gine, Valery G. Romanovski, Joan Torregrosawork_xxivy3fv5jhy5bvp6delblxmmmWed, 23 Nov 2022 00:00:00 GMTGauge Theories on kappa-Minkowski spaces: Results and prospects
https://scholar.archive.org/work/s7l5y7duhbgl5iokfntdrbkzna
Recent results obtained in -Poincaré invariant gauge theories on -Minkowski space are reviewed and commented. A Weyl quantization procedure can be applied to convolution algebras to derive a convenient star product. For such a star product, gauge invariant polynomial action functional depending on the curvature exists only in 5 dimensions. The corresponding noncommutative differential calculus and the related connection are twisted together with the BRST structure linked to the gauge invariance. Phenomenological consequences stemming from the existence of one extra dimension are commented. Some consequences of the appearance of a non-vanishing one-loop tadpole upon BRST gauge-fixing are discussed.Jean-Christophe Wallet, Kilian Hersentwork_s7l5y7duhbgl5iokfntdrbkznaWed, 23 Nov 2022 00:00:00 GMTSchrödinger's Bat: Diffusion Models Sometimes Generate Polysemous Words in Superposition
https://scholar.archive.org/work/itrrqatrdverfjzzacdyn7copy
Recent work has shown that despite their impressive capabilities, text-to-image diffusion models such as DALL-E 2 (Ramesh et al., 2022) can display strange behaviours when a prompt contains a word with multiple possible meanings, often generating images containing both senses of the word (Rassin et al., 2022). In this work we seek to put forward a possible explanation of this phenomenon. Using the similar Stable Diffusion model (Rombach et al., 2022), we first show that when given an input that is the sum of encodings of two distinct words, the model can produce an image containing both concepts represented in the sum. We then demonstrate that the CLIP encoder used to encode prompts (Radford et al., 2021) encodes polysemous words as a superposition of meanings, and that using linear algebraic techniques we can edit these representations to influence the senses represented in the generated images. Combining these two findings, we suggest that the homonym duplication phenomenon described by Rassin et al. (2022) is caused by diffusion models producing images representing both of the meanings that are present in superposition in the encoding of a polysemous word.Jennifer C. White, Ryan Cotterellwork_itrrqatrdverfjzzacdyn7copyWed, 23 Nov 2022 00:00:00 GMTMachine-learning enabled optimization of atomic structures using atoms with fractional existence
https://scholar.archive.org/work/5rdixc5st5czhhx7jizsdsi2ca
We introduce a method for global optimization of the structure of atomic systems that uses additional atoms with fractional existence. The method allows for movement of atoms over long distances bypassing energy barriers encountered in the conventional position space. The method is based on Gaussian processes, where the extrapolation to fractional existence is performed with a vectorial fingerprint. The method is applied to clusters and two-dimensional systems, where the fractional existence variables are optimized while keeping the atomic positions fixed on a lattice. Simultaneous optimization of atomic coordinates and existence variables is demonstrated on copper clusters of varying size. The existence variables are shown to speed up the global optimization of large and particularly difficult-to-optimize clusters.Casper Larsen, Sami Kaappa, Andreas Lynge Vishart, Thomas Bligaard, Karsten Wedel Jacobsenwork_5rdixc5st5czhhx7jizsdsi2caWed, 23 Nov 2022 00:00:00 GMTIs quantum computing green? An estimate for an energy-efficiency quantum advantage
https://scholar.archive.org/work/igkfocjd2bhznbepz25jf4qz5e
The quantum advantage threshold determines when a quantum processing unit (QPU) is more efficient with respect to classical computing hardware in terms of algorithmic complexity. The "green" quantum advantage threshold - based on a comparison of energetic efficiency between the two - is going to play a fundamental role in the comparison between quantum and classical hardware. Indeed, its characterization would enable better decisions on energy-saving strategies, e.g. for distributing the workload in hybrid quantum-classical algorithms. Here, we show that the green quantum advantage threshold crucially depends on (i) the quality of the experimental quantum gates and (ii) the entanglement generated in the QPU. Indeed, for NISQ hardware and algorithms requiring a moderate amount of entanglement, a classical tensor network emulation can be more energy-efficient at equal final state fidelity than quantum computation. We compute the green quantum advantage threshold for a few paradigmatic examples in terms of algorithms and hardware platforms, and identify algorithms with a power-law decay of singular values of bipartitions - with power-law exponent α≲ 1 - as the green quantum advantage threshold in the near future.Daniel Jaschke, Simone Montangerowork_igkfocjd2bhznbepz25jf4qz5eTue, 22 Nov 2022 00:00:00 GMTA Depolarizing Noise-aware Transpiler for Optimal Amplitude Amplification
https://scholar.archive.org/work/yilyqiaoe5cfna3nb3vhtbwd7a
Amplitude amplification provides a quadratic speed-up for an array of quantum algorithms when run on a quantum machine perfectly isolated from its environment. However, the advantage is substantially diminished as the NISQ-era quantum machines lack the large number of qubits necessary to provide error correction. Noise in the computation grows with the number of gate counts in the circuit with each iteration of amplitude amplification. After a certain number of amplifications, the loss in accuracy from the gate noise starts to overshadow the gain in accuracy due to amplification, forming an inflection point. Beyond this point, accuracy continues to deteriorate until the machine reaches a maximally mixed state where the result is uniformly random. Hence, quantum transpilers should take the noise parameters of the underlying quantum machine into consideration such that the circuit can be optimized to attain the maximal accuracy possible for that machine. In this work, we propose an extension to the transpiler that predicts the accuracy of the result at every amplification with high fidelity by applying pure Bayesian analysis to individual gate noise rates. Using this information, it finds the inflection point and optimizes the circuit by halting amplification at that point. The prediction is made without needing to execute the circuit either on a quantum simulator or an actual quantum machine.Debashis Ganguly, Wonsun Ahnwork_yilyqiaoe5cfna3nb3vhtbwd7aTue, 22 Nov 2022 00:00:00 GMTSearch for electroweak production of supersymmetric particles in compressed mass spectra with the ATLAS detector at the LHC
https://scholar.archive.org/work/syrsys6kc5cv5ohkityim6kady
Two analyses searching for the production of supersymmetric particles through the electroweak interaction are presented: the chargino search, targeting the pair production of charginos decaying into W bosons and neutralinos, and the displaced track search, looking for charged tracks arising from the decays of higgsinos into pions. These searches target compressed phase spaces, where the mass difference between the next-to-lightest and lightest supersymmetric particle is relatively small. The searches use proton-proton collision data collected at a centre-of-mass energy of 13 TeV with the ATLAS detector at the LHC. In the chargino search, the targeted mass difference between charginos and neutralinos is close to the mass of the W boson. In such phase space, the chargino pair production is kinematically similar to the WW background, making the chargino signal experimentally challenging to be discriminated from the WW background. Machine learning techniques are adopted to separate the supersymmetric signal from the backgrounds. The results exclude chargino masses up to about 140 GeV for mass splittings down to about 100 GeV, superseding the previous results in particularly interesting regions where the chargino pair production could have hidden behind the looking-alike WW background. In the displaced track search, the mass difference between the produced sparticles and the lightest neutralinos goes down to 0.3 GeV. The experimental signature has a low momentum charged track with an origin displaced from the collision point. The results show that the analysis has the sensitivity to exclude different hypotheses for higgsino masses up to 175 GeV if no excess is observed in data. For lower masses, the larger signal cross-section allows to achieve higher significance for different mass splitting scenarios. All these signal hypotheses have not been probed by any existing analysis of LHC data.Eric Ballabenework_syrsys6kc5cv5ohkityim6kadyTue, 22 Nov 2022 00:00:00 GMT