A5045706381- Quantum Computing Algorithms and Architecture
- Quantum Information and Cryptography
- Quantum and electron transport phenomena
- Quantum Mechanics and Applications
- Quantum-Dot Cellular Automata
- Quantum many-body systems
- Neural Networks and Reservoir Computing
- Diamond and Carbon-based Materials Research
- Tensor decomposition and applications
- Advanced Thermodynamics and Statistical Mechanics
- Particle physics theoretical and experimental studies
- Advanced Fiber Laser Technologies
- Particle Detector Development and Performance
- Quantum, superfluid, helium dynamics
- Parallel Computing and Optimization Techniques
- Quantum optics and atomic interactions
- Laser-Matter Interactions and Applications
- Force Microscopy Techniques and Applications
- Digital Filter Design and Implementation
- Atomic and Subatomic Physics Research
- Opinion Dynamics and Social Influence
- Optical Network Technologies
- History and advancements in chemistry
- Black Holes and Theoretical Physics
- Semiconductor materials and devices
IQM (Finland)
2022-2024
Xanadu Quantum Technologies (Canada)
2019-2021
Technical University of Munich
2013-2019
Munich Center for Quantum Science and Technology
2019
Institute for Scientific Interchange
2013-2016
Harvard University
2011
Aalto University
2011
Helsinki Institute of Physics
2004-2008
University of Helsinki
2004-2005
An important application for near-term quantum computing lies in optimization tasks, with applications ranging from chemistry and drug discovery to machine learning. In many settings --- most prominently so-called parametrized or variational algorithms the objective function is a result of hybrid quantum-classical processing. To optimize objective, it useful have access exact gradients circuits respect gate parameters. This paper shows how expectation values measurements can be estimated...
PennyLane is a Python 3 software framework for differentiable programming of quantum computers. The library provides unified architecture near-term computing devices, supporting both qubit and continuous-variable paradigms. PennyLane's core feature the ability to compute gradients variational circuits in way that compatible with classical techniques such as backpropagation. thus extends automatic differentiation algorithms common optimization machine learning include hybrid computations. A...
We consider a generic elementary gate sequence which is needed to implement general quantum acting on n qubits-a unitary transformation with 4(n) degrees of freedom. For synthesizing the sequence, method based so-called cosine-sine matrix decomposition presented. The result optimal in number one-qubit gates, 4(n), and scales more favorably than previously reported decompositions requiring 4(n)-2(n+1) controlled NOT gates.
Abstract In quantum sensing, precision is typically limited by the maximum time interval over which phase can be accumulated. Memories have been used to enhance this beyond coherence lifetime and thus gain precision. Here, we demonstrate that using a memory an increased sensitivity also achieved. To end, use entanglement in hybrid spin system comprising sensing qubit associated with single nitrogen-vacancy centre diamond. With retain full state even after decay of sensor, enables coherent...
\emph{Ab initio} computation of molecular properties is one the most promising applications quantum computing. While this problem widely believed to be intractable for classical computers, efficient algorithms exist which have potential vastly accelerate research throughput in fields ranging from material science drug discovery. Using a solid-state register realized nitrogen-vacancy (NV) defect diamond, we compute bond dissociation curve minimal basis helium hydride cation, HeH$^+$....
Tensor network methods are taking a central role in modern quantum physics and beyond. They can provide an efficient approximation to certain classes of states, the associated graphical language makes it easy describe pictorially reason about circuits, channels, protocols, open systems more. Our goal is explain tensor networks some as quickly painlessly possible. Beginning with key definitions, presented through examples. We then introduction matrix product states. conclude tutorial...
We introduce Strawberry Fields, an open-source quantum programming architecture for light-based computers, and detail its key features. Built in Python, Fields is a full-stack library design, simulation, optimization, machine learning of continuous-variable circuits. The platform consists three main components: (i) API based on easy-to-use language named Blackbird; (ii) suite virtual computer backends, built NumPy TensorFlow, each targeting specialized uses; (iii) engine which can compile...
Tunable coupling of superconducting qubits has been widely studied due to its importance for isolated gate operations in scalable quantum processor architectures. Here, we demonstrate a tunable qubit-qubit coupler based on floating transmon device, which allows us place at least 2 mm apart from each other while maintaining over 50-MHz between the and qubits. In introduced tunable-coupler design, both qubit-coupler couplings are mediated by two waveguides instead relying direct capacitive...
Uniformly controlled one-qubit gates are quantum which can be represented as direct sums of two-dimensional unitary operators acting on a single qubit. We present gate array implements any $n$-qubit this type using at most ${2}^{n\ensuremath{-}1}\ensuremath{-}1$ controlled-NOT gates, ${2}^{n\ensuremath{-}1}$ and diagonal gate. To illustrate the versatility these we then apply them to decomposition general state preparation procedure. Moreover, study their implementation only nearest-neighbor...
We consider a unitary transformation which maps any given pure state of an $n$-qubit quantum register into another one. This has applications in the initialization computer, and also some algorithms. Employing uniformly controlled rotations, we present circuit $2^{n+2}-4n-4$ CNOT gates $2^{n+2}-5$ one-qubit elementary rotations that effects transformation. The complexity is noticeably lower than previously published results. Moreover, analytic expression for rotation angles needed
Quantum optimal control theory is applied to two and three coupled Josephson charge qubits. It shown that by using shaped pulses a CNOT gate can be obtained with trace fidelity > 0.99999 for the qubits, even when including higher states, leakage below 1%. Yet, required time only fifth of pioneering experiment [T. Yamamoto et al., Nature 425 (2003), 941] otherwise identical parameters. The controls have palindromic smooth courses representable superpositions few harmonics. We outline schemes...
Determining community structure is a central topic in the study of complex networks, be it technological, social, biological or chemical, static interacting systems. In this paper, we extend concept detection from classical to quantum systems—a crucial missing component theory networks based on mechanics. We demonstrate that certain mechanical effects cannot captured using current network tools and provide new methods overcome these problems. Our approaches are defining closeness measures...
Given its importance to many other areas of physics, from condensed matter physics thermodynamics, time-reversal symmetry has had relatively little influence on quantum information science. Here we develop a network-based picture theory, classifying Hamiltonians and circuits as time-symmetric or not in terms the elements geometries their underlying networks. Many typical science are found exhibit time-asymmetry. Moreover, show that time-asymmetry can be controlled using local gates only,...
We consider a unitary transformation which maps any given state of an n-qubit quantum register into another one. This has applications in the initialization computer, and also some algorithms. Employing uniformly controlled rotations, we present circuit 2n+2 - 4n 4 CNOT gates 5 one-qubit elementary rotations that effects transformation. The complexity is noticeably lower than previously published results. Moreover, analytic expression for rotation angles needed
In his famous 1981 talk, Feynman proposed that unlike classical computers, which would presumably experience an exponential slowdown when simulating quantum phenomena, a universal simulator not. An ideal be controllable, and built using existing technology. some cases, moving away from gate-model-based implementations of computing may offer more feasible solution for particular experimental implementations. Here we consider adiabatic simulates the ground state properties sparse Hamiltonians...
Cavity optomechanical systems are one of the leading experimental platforms for controlling mechanical motion in quantum regime. We exemplify that control over cavity greatly increases by coupling also to a two-level system, thereby creating hybrid system. If system can be driven largely independently cavity, we show non-linearity thus introduced enables us steer extended non-classical target states oscillator with Wigner functions exhibiting significant negative regions. illustrate how use...
Abstract With a growing interest in quantum technology globally, there is an increasing need for accessing relevant physical systems education and research. In this paper we introduce commercially available on-site computer utilizing superconducting technology, offering insights into its fundamental hardware software components. We show how system can be used to teach concepts deepen understanding of theory computing. It offers learning opportunities future talent contributes technological...
We investigate the generation of quantum operations for one-qubit systems under classical Markovian noise with a $1/{f}^{\ensuremath{\alpha}}$ power spectrum, where $2>\ensuremath{\alpha}>0$. present an efficient way to approximate discrete multistate fluctuator. With this method, average temporal evolution qubit state operator can be feasibly determined from recently derived deterministic master equations. obtain such as memory and NOT gate high fidelity by gradient-based optimization...
Silicon detectors for the Roman Pots of large hadron collider TOTEM experiment aim full sensitivity at edge where a terminating structure is required electrical stability. This work provides an innovative approach reducing conventional width to less than 100 microns, still using standard planar fabrication technology. The objective this new development decouple electric behaviour surface from sensitive volume within tens microns. explanation basic principle together with experimental...
In this paper, we extend past work done on the application of mathematics category theory to quantum information science. Specifically, present a realization dagger-compact that can model finite-dimensional systems and explicitly allows for interaction arbitrary, possibly unequal, dimensions. Hence our framework handle generic tensor network states, including matrix product states. Our categorical subsumes traditional circuit while remaining directly easily applicable problems stated in...
Invariant theory is concerned with functions that do not change under the action of a given group. Here we communicate an approach based on tensor networks to represent polynomial local unitary invariants quantum states. This graphical provides alternative equations describe invariants, which often contain large number terms coefficients raised high powers. also enables one use known methods from network (such as matrix product state (MPS) factorization) when studying invariants. As our main...
We study the dynamics of quantum systems under classical and noise, focusing on decoherence in qubit systems. Classical noise is described by a random process leading to stochastic temporal evolution closed system, whereas originates from coupling microscopic system its macroscopic environment. derive deterministic master equations describing average continuous-time Markovian two sets noise. Strikingly, these three motion are shown be equivalent case telegraph proper environments. Hence...