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The relative power of quantum algorithms, using an adaptive access to quantum devices, versus classical post-processing methods that rely only on an initial quantum data set, remains the subject of active debate. Here, we present evidence…

Quantum Physics · Physics 2025-10-02 Oleksandr Kyriienko , Chukwudubem Umeano , Zoë Holmes

For years, the quantum/reversible circuit community has been convinced that: a) the addition of auxiliary qubits is instrumental in constructing a smaller quantum circuit; and, b) the introduction of quantum gates inside reversible circuits…

Quantum Physics · Physics 2011-08-01 Dmitri Maslov , Mehdi Saeedi

Contemporary methods for benchmarking noisy quantum processors typically measure average error rates or process infidelities. However, thresholds for fault-tolerant quantum error correction are given in terms of worst-case error rates --…

We study how to utilize (possibly erroneous) predictions in a model for computing under uncertainty in which an algorithm can query unknown data. Our aim is to minimize the number of queries needed to solve the minimum spanning tree…

Data Structures and Algorithms · Computer Science 2022-07-01 Thomas Erlebach , Murilo Santos de Lima , Nicole Megow , Jens Schlöter

We consider the sequential quantum channel discrimination problem using adaptive and non-adaptive strategies. In this setting the number of uses of the underlying quantum channel is not fixed but a random variable that is either bounded in…

Information Theory · Computer Science 2022-10-21 Yonglong Li , Christoph Hirche , Marco Tomamichel

In some quantum algorithms, arithmetic operations are of utmost importance for resource estimation. In binary quantum systems, some efficient implementation of arithmetic operations like, addition/subtraction, multiplication/division,…

Quantum Physics · Physics 2022-06-01 Amit Saha , Turbasu Chatterjee , Anupam Chattopadhyay , Amlan Chakrabarti

In its many variants, randomized benchmarking (RB) is a broadly used technique for assessing the quality of gate implementations on quantum computers. A detailed theoretical understanding and general guarantees exist for the functioning and…

Quantum Physics · Physics 2023-06-28 Markus Heinrich , Martin Kliesch , Ingo Roth

Typical quantum gate tomography protocols struggle with a self-consistency problem: the gate operation cannot be reconstructed without knowledge of the initial state and final measurement, but such knowledge cannot be obtained without…

Quantum computers are poised to radically outperform their classical counterparts by manipulating coherent quantum systems. A realistic quantum computer will experience errors due to the environment and imperfect control. When these errors…

Quantum Physics · Physics 2016-11-21 Joel J. Wallman , Joseph Emerson

With a combination of the quantum repeater and the cluster state approaches, we show that efficient quantum computation can be constructed even if all the entangling quantum gates only succeed with an arbitrarily small probability $p$. The…

Quantum Physics · Physics 2009-11-11 L. -M. Duan , R. Raussendorf

In communication complexity-like problems, previous studies have shown either an exponential quantum advantage or an unbounded quantum advantage with an exponentially large input set $\Theta(2^{n})$ bits with respect to classical…

In parity quantum computing, multi-qubit logical gates are implemented by single-qubit rotations on a suitably encoded state involving auxiliary qubits. Consequently, there is a correspondence between qubit count and the size of the native…

We revisit the sequential variants of linear regression with the squared loss, classification problems with hinge loss, and logistic regression, all characterized by unbounded losses in the setup where no assumptions are made on the…

Machine Learning · Statistics 2025-09-08 Jian Qian , Alexander Rakhlin , Nikita Zhivotovskiy

Quantum states obey an asymptotic no-cloning theorem, stating that no deterministic machine can reliably replicate generic sequences of identically prepared pure states. In stark contrast, we show that generic sequences of unitary gates can…

Quantum Physics · Physics 2015-04-01 G. Chiribella , Y. Yang , C. Huang

We present characterisations of "exact" gap-definable classes, in terms of indeterministic models of computation which slightly modify the standard model of quantum computation. This follows on work of Aaronson [arXiv:quant-ph/0412187], who…

Computational Complexity · Computer Science 2015-09-28 Niel de Beaudrap

We present an extension of Adiabatic Quantum Computing (AQC) algorithm for the unstructured search to the case when the number of marked items is unknown. The algorithm maintains the optimal Grover speedup and includes a small counting…

Mathematical Physics · Physics 2015-03-17 Zhenwei Cao , Alexander Elgart

Transversal gates play a crucial role in suppressing error propagation in fault-tolerant quantum computation, yet they are intrinsically constrained: any nontrivial code encoding a single logical qubit admits only a finite subgroup of…

Quantum Physics · Physics 2025-04-30 Chao Zhang , Zipeng Wu , Shilin Huang , Bei Zeng

Unmeasured confounding is a threat to causal inference and gives rise to biased estimates. In this article, we consider the problem of individualized decision-making under partial identification. Firstly, we argue that when faced with…

Methodology · Statistics 2021-10-22 Yifan Cui

We study set selection problems where the weights are uncertain. Instead of its exact weight, only an uncertainty interval containing its true weight is available for each element. In some cases, some solutions are universally optimal;…

Data Structures and Algorithms · Computer Science 2024-04-29 Christoph Dürr , Arturo Merino , José A. Soto , José Verschae

Predictive algorithms inform consequential decisions in settings with selective labels: outcomes are observed only for units selected by past decision makers. This creates an identification problem under unobserved confounding -- when…

Econometrics · Economics 2025-11-07 Ashesh Rambachan , Amanda Coston , Edward Kennedy