đź“°News:

- The Quantum Revolution Is Here, Its Name Is Hybrid
- Hyundai Motor and IonQ partner to use Quantum Computing for object detection
- Memristors: Quantum computing breakthrough could take us back to the multiverse
- WHAT IS QUANTUM MACHINE LEARNING? APPLICATIONS OF QUANTUM MACHINE LEARNING

đź“˝Videos:

- Quantum Machine Learning vs. Machine Learning for Quantum Computing by Mats Granath
- IONQ + Hyundai | Quantum Machine Learning
- Anatole von Lilienfeld: Quantum Machine Learning
- Advances in Quantum Machine Intelligence (Pooya Ronagh, PhD)
- Revealing quantum dynamical universality with neural quantum states | Markus Schmitt

đź‘¨â€Ťđź’»Developers:

## MCBeth: A Measurement Based Quantum Programming Language

Aidan Evans,Â Seun Omonije,Â Robert SoulĂ©,Â Robert Rand

Apr 25 2022Â cs.PLÂ quant-phÂ arXiv:2204.10784v1

Gate-based quantum programming languages are ubiquitous but measurement-based languages currently exist only on paper. This work introduces MCBeth, a quantum programming language which allows programmers to directly represent, program, and simulate measurement-based and cluster state computation by building upon the measurement calculus. While MCBeth programs are meant to be executed directly on hardware, to take advantage of current machines we also provide a compiler to gate-based instructions. We argue that there are clear advantages to measurement-based quantum computation compared to gate-based when it comes to implementing common quantum algorithms and distributed quantum computation.

## LOv-Calculus: A Graphical Language for Linear Optical Quantum Circuits

Alexandre ClĂ©ment,Â Nicolas Heurtel,Â Shane Mansfield,Â Simon Perdrix,Â BenoĂ®t Valiron

Apr 26 2022Â quant-phÂ cs.LOÂ arXiv:2204.11787v1

We introduce the LOv-calculus, a graphical language for reasoning about linear optical quantum circuits with so-called vacuum state auxiliary inputs. We present the axiomatics of the language and prove its soundness and completeness: two LOv-circuits represent the same quantum process if and only if one can be transformed into the other with the rules of the LOv-calculus. We give a confluent and terminating rewrite system to rewrite any polarisation-preserving LOv-circuit into a unique triangular normal form, inspired by the universal decomposition of Reck et al. (1994) for linear optical quantum circuits.

## Qunity: A Unified Language for Quantum and Classical Computing

Finn Voichick,Â Robert Rand,Â Michael Hicks

Apr 27 2022Â cs.PLÂ cs.LOÂ quant-phÂ arXiv:2204.12384v1

We introduce Qunity, a new quantum programming language designed around the central goal of treating quantum computing as a natural generalization of classical computing. Qunity presents a unified syntax where familiar programming constructs can have both quantum and classical effects. For example, one can use sum types to implement the direct sum of linear operators, exception handling syntax to implement projective measurements, and aliasing to induce entanglement. Further, Qunity takes advantage of the overlooked BQP subroutine theorem, allowing one to construct reversible subroutines from irreversible quantum algorithms through the uncomputation of “garbage” outputs. Unlike existing languages that enable quantum aspects with a separate add-on (e.g., gates added to a classical language), we unify quantum and classical computing through novel compositional semantics based on Kraus operators. We present Qunity’s syntax, type system, and denotational semantics, showing how it can cleanly express several quantum algorithms. We also outline how Qunity could be compiled to OpenQASM, demonstrating the realizability of our design.

đź“—Papers:

## Quantifying Unknown Quantum Entanglement via a Hybrid Quantum-Classical Machine Learning Framework

Xiaodie Lin,Â Zhenyu Chen,Â Zhaohui Wei

Apr 26 2022Â quant-phÂ cs.LGÂ arXiv:2204.11500v1

Quantifying unknown quantum entanglement experimentally is a difficult task, but also becomes more and more necessary because of the fast development of quantum engineering. Machine learning provides practical solutions to this fundamental problem, where one has to train a proper machine learning model to predict entanglement measures of unknown quantum states based on experimentally measurable data, say moments or correlation data produced by local measurements. In this paper, we compare the performance of these two different machine learning approaches systematically. Particularly, we first show that the approach based on moments enjoys a remarkable advantage over that based on correlation data, though the cost of measuring moments is much higher. Next, since correlation data is much easier to obtain experimentally, we try to better its performance by proposing a hybrid quantum-classical machine learning framework for this problem, where the key is to train optimal local measurements to generate more informative correlation data. Our numerical simulations show that the new framework brings us comparable performance with the approach based on moments to quantify unknown entanglement. Our work implies that it is already practical to fulfill such tasks on near-term quantum devices.

## Neural-Network Decoders for Measurement Induced Phase Transitions

Hossein Dehghani,Â Ali Lavasani,Â Mohammad Hafezi,Â Michael J. Gullans

Apr 26 2022Â quant-phÂ cond-mat.dis-nnÂ cond-mat.stat-mechÂ cond-mat.str-elÂ arXiv:2204.10904v1

Open quantum systems have been shown to host a plethora of exotic dynamical phases. Measurement-induced entanglement phase transitions in monitored quantum systems are a striking example of this phenomena. However, naive realizations of such phase transitions requires an exponential number of repetitions of the experiment which is practically unfeasible on large systems. Recently, it has been proposed that these phase transitions can be probed locally via entangling reference qubits and studying their purification dynamics. In this work, we leverage modern machine learning tools to devise a neural network decoder to determine the state of the reference qubits conditioned on the measurement outcomes. We show that the entanglement phase transition manifests itself as a stark change in the learnability of the decoder function. We study the complexity and scalability of this approach and discuss how it can be utilized to detect entanglement phase transitions in generic experiments.

## Data compression for quantum machine learning

Rohit Dilip,Â Yu-Jie Liu,Â Adam Smith,Â Frank Pollmann

Apr 26 2022Â quant-phÂ cond-mat.dis-nnÂ arXiv:2204.11170v1

The advent of noisy-intermediate scale quantum computers has introduced the exciting possibility of achieving quantum speedups in machine learning tasks. These devices, however, are composed of a small number of qubits, and can faithfully run only short circuits. This puts many proposed approaches for quantum machine learning beyond currently available devices. We address the problem of efficiently compressing and loading classical data for use on a quantum computer. Our proposed methods allow both the required number of qubits and depth of the quantum circuit to be tuned. We achieve this by using a correspondence between matrix-product states and quantum circuits, and further propose a hardware-efficient quantum circuit approach, which we benchmark on the Fashion-MNIST dataset. Finally, we demonstrate that a quantum circuit based classifier can achieve competitive accuracy with current tensor learning methods using only 11 qubits.

## Quantum-classical convolutional neural networks in radiological image classification

Andrea Matic,Â Maureen Monnet,Â Jeanette Miriam Lorenz,Â Balthasar Schachtner,Â Thomas Messerer

Apr 27 2022Â quant-phÂ cs.AIÂ arXiv:2204.12390v1

Quantum machine learning is receiving significant attention currently, but its usefulness in comparison to classical machine learning techniques for practical applications remains unclear. However, there are indications that certain quantum machine learning algorithms might result in improved training capabilities with respect to their classical counterparts – which might be particularly beneficial in situations with little training data available. Such situations naturally arise in medical classification tasks. Within this paper, different hybrid quantum-classical convolutional neural networks (QCCNN) with varying quantum circuit designs and encoding techniques are proposed. They are applied to two- and three-dimensional medical imaging data, e.g. featuring different, potentially malign, lesions in computed tomography scans. The performance of these QCCNNs is already similar to the one of their classical counterparts – therefore encouraging further studies towards the direction of applying these algorithms within medical imaging tasks.

## Quantum Semi-Supervised Kernel Learning

Seyran Saeedi,Â Aliakbar Panahi,Â Tom Arodz

Apr 25 2022Â cs.LGÂ quant-phÂ arXiv:2204.10700v1

Quantum computing leverages quantum effects to build algorithms that are faster then their classical variants. In machine learning, for a given model architecture, the speed of training the model is typically determined by the size of the training dataset. Thus, quantum machine learning methods have the potential to facilitate learning using extremely large datasets. While the availability of data for training machine learning models is steadily increasing, oftentimes it is much easier to collect feature vectors that to obtain the corresponding labels. One of the approaches for addressing this issue is to use semi-supervised learning, which leverages not only the labeled samples, but also unlabeled feature vectors. Here, we present a quantum machine learning algorithm for training Semi-Supervised Kernel Support Vector Machines. The algorithm uses recent advances in quantum sample-based Hamiltonian simulation to extend the existing Quantum LS-SVM algorithm to handle the semi-supervised term in the loss. Through a theoretical study of the algorithm’s computational complexity, we show that it maintains the same speedup as the fully-supervised Quantum LS-SVM.

## Grover Search Inspired Alternating Operator Ansatz of Quantum Approximate Optimization Algorithm for Search Problems

Chen-Fu Chiang,Â Paul M. Alsing

Apr 25 2022Â quant-phÂ arXiv:2204.10324v1

We use the mapping between two computation frameworks , Adiabatic Grover Search (AGS) and Adiabatic Quantum Computing (AQC), to translate the Grover search algorithm into the AQC regime. We then apply Trotterization on the schedule-dependent Hamiltonian of AGS to obtain the values of variational parameters in the Quantum Approximate Optimization Algorithm (QAOA) framework. The goal is to carry the optimal behavior of Grover search algorithm into the QAOA framework without the iterative machine learning processes.

## Neural-Network Quantum States: A Systematic Review

David R. Vivas,Javier MadroĂ±ero,Victor Bucheli,Luis O. GĂłmez,John H. Reina

Apr 28 2022Â quant-phÂ arXiv:2204.12966v1

The so-called contemporary AI revolution has reached every corner of the social, human and natural sciences — physics included. In the context of quantum many-body physics, its intersection with machine learning has configured a high-impact interdisciplinary field of study; with the arise of recent seminal contributions that have derived in a large number of publications. One particular research line of such field of study is the so-called Neural-Network Quantum States, a powerful variational computational methodology for the solution of quantum many-body systems that has proven to compete with well-established, traditional formalisms. Here, a systematic review of literature regarding Neural-Network Quantum States is presented

## Reinforcement Learning Generation of 4-Qubits Entangled States

Sara Giordano,Â Miguel A. Martin-Delgado

Apr 27 2022Â quant-phÂ arXiv:2204.12351v1

We have devised an artificial intelligence algorithm with machine reinforcement learning (Q-learning) to construct remarkable entangled states with 4 qubits. This way, the algorithm is able to generate representative states for some of the 49 true SLOCC classes of the four-qubit entanglement states. In particular, it is possible to reach at least one true SLOCC class for each of the nine entanglement families. The quantum circuits synthesized by the algorithm may be useful for the experimental realization of these important classes of entangled states and to draw conclusions about the intrinsic properties of our universe. We introduce a graphical tool called the state-link graph (SLG) to represent the construction of the Quality matrix (Q-matrix) used by the algorithm to build a given objective state belonging to the corresponding entanglement class. This allows us to discover the necessary connections between specific entanglement features and the role of certain quantum gates that the algorithm needs to include in the quantum gate set of actions. The quantum circuits found are optimal by construction with respect to the quantum gate-set chosen. These SLGs make the algorithm simple, intuitive and a useful resource for the automated construction of entangled states with a low number of qubits.

## Neural annealing and visualization of autoregressive neural networks in the Newman-Moore model

Estelle M. Inack,Â Stewart Morawetz,Â Roger G. Melko

Apr 26 2022Â cond-mat.dis-nnÂ cond-mat.stat-mechÂ quant-phÂ arXiv:2204.11272v1

Artificial neural networks have been widely adopted as ansatzes to study classical and quantum systems. However, some notably hard systems such as those exhibiting glassiness and frustration have mainly achieved unsatisfactory results despite their representational power and entanglement content, thus, suggesting a potential conservation of computational complexity in the learning process. We explore this possibility by implementing the neural annealing method with autoregressive neural networks on a model that exhibits glassy and fractal dynamics: the two-dimensional Newman-Moore model on a triangular lattice. We find that the annealing dynamics is globally unstable because of highly chaotic loss landscapes. Furthermore, even when the correct ground state energy is found, the neural network generally cannot find degenerate ground-state configurations due to mode collapse. These findings indicate that the glassy dynamics exhibited by the Newman-Moore model caused by the presence of fracton excitations in the configurational space likely manifests itself through trainability issues and mode collapse in the optimization landscape.

## Towards Bundle Adjustment for Satellite Imaging via Quantum Machine Learning

Nico Piatkowski,Â Thore Gerlach,Â Romain Hugues,Â Rafet Sifa,Â Christian Bauckhage,Â Frederic Barbaresco

Apr 26 2022Â quant-phÂ cs.CVÂ stat.MLÂ arXiv:2204.11133v1

Given is a set of images, where all images show views of the same area at different points in time and from different viewpoints. The task is the alignment of all images such that relevant information, e.g., poses, changes, and terrain, can be extracted from the fused image. In this work, we focus on quantum methods for keypoint extraction and feature matching, due to the demanding computational complexity of these sub-tasks. To this end, k-medoids clustering, kernel density clustering, nearest neighbor search, and kernel methods are investigated and it is explained how these methods can be re-formulated for quantum annealers and gate-based quantum computers. Experimental results obtained on digital quantum emulation hardware, quantum annealers, and quantum gate computers show that classical systems still deliver superior results. However, the proposed methods are ready for the current and upcoming generations of quantum computing devices which have the potential to outperform classical systems in the near future.

## How to Approximate any Objective Function via Quadratic Unconstrained Binary Optimization

Thomas Gabor,Â Marian Lingsch Rosenfeld,Â Sebastian Feld,Â Claudia Linnhoff-Popien

Apr 26 2022Â quant-phÂ arXiv:2204.11035v1

Quadratic unconstrained binary optimization (QUBO) has become the standard format for optimization using quantum computers, i.e., for both the quantum approximate optimization algorithm (QAOA) and quantum annealing (QA). We present a toolkit of methods to transform almost arbitrary problems to QUBO by (i) approximating them as a polynomial and then (ii) translating any polynomial to QUBO. We showcase the usage of our approaches on two example problems (ratio cut and logistic regression).

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