Strategies for quantum computing molecular energies using the unitary coupled cluster ansatz
- J. Romero, R. Babbush, J. McClean, Cornelius Hempel, P. Love, A. Aspuru‐Guzik
- Computer ScienceQuantum Science and Technology
- 10 January 2017
The application of VQE to the simulation of molecular energies using the unitary coupled cluster (UCC) ansatz is studied and an analytical method to compute the energy gradient is proposed that reduces the sampling cost for gradient estimation by several orders of magnitude compared to numerical gradients.
Quasiparticle engineering and entanglement propagation in a quantum many-body system
- P. Jurcevic, B. Lanyon, C. Roos
- PhysicsNature
- 21 January 2014
First, the entanglement distributed by quasiparticles as they trace out light-cone-like wavefronts is observed, and second, using the ability to tune the interaction range in the system, information propagation is observed in an experimental regime where the effective-light-cone picture does not apply.
Quantum Chemistry Calculations on a Trapped-Ion Quantum Simulator
- Cornelius Hempel, C. Maier, C. Roos
- PhysicsPhysical Review X
- 27 March 2018
Quantum-classical hybrid algorithms are emerging as promising candidates for near-term practical applications of quantum information processors in a wide variety of fields ranging from chemistry to…
Quantum simulation of the Klein paradox with trapped ions.
- R. Gerritsma, B. Lanyon, C. Roos
- PhysicsPhysical Review Letters
- 21 July 2010
By precisely engineering a range of external potentials, this work is able to simulate text book relativistic scattering experiments and study Klein tunneling in an analogue quantum simulator and describe extensions to solve problems that are beyond current classical computing capabilities.
Direct Observation of Dynamical Quantum Phase Transitions in an Interacting Many-Body System.
- P. Jurcevic, H. Shen, C. Roos
- PhysicsPhysical Review Letters
- 20 December 2016
This work investigates and measures dynamical quantum phase transitions in a string of ions simulating interacting transverse-field Ising models, and establishes a link between DQPTs and the dynamics of other quantities such as the magnetization.
Observation of entangled states of a fully-controlled 20 qubit system
We generate and characterise entangled states of a register of 20 individually-controlled qubits, where each qubit is encoded into the electronic state of a trapped atomic ion. Entanglement is…
Measurement-based quantum computation with trapped ions.
- B. Lanyon, P. Jurcevic, C. Roos
- Computer Science, PhysicsPhysical Review Letters
- 23 August 2013
The principles of measurement-based quantum computation using deterministically generated cluster states, in a system of trapped calcium ions, are demonstrated and a universal set of operations for quantum computing is implemented.
Spectroscopy of Interacting Quasiparticles in Trapped Ions.
- P. Jurcevic, P. Hauke, C. Roos
- PhysicsPhysical Review Letters
- 8 May 2015
A spectroscopic technique to study artificial quantum matter and use it for characterizing quasiparticles in a many-body system of trapped atomic ions, suitable for verifying quantum simulators by tuning them into regimes where the collective excitations have a simple form.
Efficient tomography of a quantum many-body system
Traditionally quantum state tomography is used to characterize a quantum state, but it becomes exponentially hard with the system size. An alternative technique, matrix product state tomography, is…
Environment-Assisted Quantum Transport in a 10-qubit Network.
- C. Maier, T. Brydges, C. Roos
- PhysicsPhysical Review Letters
- 20 September 2018
The approach represents a controlled and scalable way to investigate quantum transport in many-body networks under static disorder and dynamic noise and shows that dephasing characterized by non-Markovian noise can maintain coherences longer than white noise dephase, with a strong influence of the spectral structure on the transport efficiency.
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