Search results for "TRAPPED ION"

Simulating open quantum systems with trapped ions

2005

This paper focuses on the possibility of simulating the open system dynamics of a paradigmatic model, namely the damped harmonic oscillator, with single trapped ions. The key idea consists in using a controllable physical system, i.e. a single trapped ion interacting with an engineered reservoir, to simulate the dynamics of other open systems usually difficult to study. The exact dynamics of the damped harmonic oscillator under very general conditions is firstly derived. Some peculiar characteristic of the system’s dynamics are then presented. Finally a way to implement with trapped ion the specific quantum simulator of interest is discussed.

Controlling Fast Transport of Cold Trapped Ions

2012

We realize fast transport of ions in a segmented micro-structured Paul trap. The ion is shuttled over a distance of more than 10^4 times its groundstate wavefunction size during only 5 motional cycles of the trap (280 micro meter in 3.6 micro seconds). Starting from a ground-state-cooled ion, we find an optimized transport such that the energy increase is as low as 0.10 $\pm$ 0.01 motional quanta. In addition, we demonstrate that quantum information stored in a spin-motion entangled state is preserved throughout the transport. Shuttling operations are concatenated, as a proof-of-principle for the shuttling-based architecture to scalable ion trap quantum computing.

Arbitrary state controlled-unitary gate by adiabatic passage

2006

We propose a robust scheme involving atoms fixed in an optical cavity to directly implement the universal controlled-unitary gate. The present technique based on adiabatic passage uses novel dark states well suited for the controlled-rotation operation. We show that these dark states allow the robust implementation of a gate that is a generalisation of the controlled-unitary gate to the case where the control qubit can be selected to be an arbitrary state. This gate has potential applications to the rapid implementation of quantum algorithms such as of the projective measurement algorithm. This process is decoherence-free since excited atomic states and cavity modes are not populated during…

Entanglement of superconducting qubits via microwave fields: Classical and quantum regimes

2008

We study analytically and numerically the problem of two qubits with fixed coupling irradiated with quantum or classical fields. In the classical case, we derive an effective Hamiltonian, and construct composite pulse sequences leading to a CNOT gate. In the quantum case, we show that qubit-qubit-photon multiparticle entanglement and maximally entangled two-qubit state can be obtained by driving the system at very low powers (one quanta of excitation). Our results can be applied to a variety of systems of two superconducting qubits coupled to resonators.

Microwave-induced coupling of superconducting qubits

2008

We investigate the quantum dynamics of a system of two coupled superconducting qubits under microwave irradiation. We find that, with the qubits operated at the charge co-degeneracy point, the quantum evolution of the system can be described by a new effective Hamiltonian which has the form of two coupled qubits with tunable coupling between them. This Hamiltonian can be used for experimental tests on macroscopic entanglement and for implementing quantum gates.

Reconstructing the vibrational state of a trapped ion

2002

A new approach for reconstructing the vibrational quantum state of a trapped ion is proposed. The method rests upon the current ability of manipulating the trapped ion state and on the possibility of effectively measuring the scalar product of the two vibrational cofactors of a vibronic entangled state. The experimental feasibility of the method is briefly discussed.

Observing the phase space trajectory of an entangled matter wave packet

2010

We observe the phase space trajectory of an entangled wave packet of a trapped ion with high precision. The application of a spin dependent light force on a superposition of spin states allows for coherent splitting of the matter wave packet such that two distinct components in phase space emerge. We observe such motion with a precision of better than 9% of the wave packet extension in both momentum and position, corresponding to a 0.8 nm position resolution. We accurately study the effect of the initial ion temperature on the quantum entanglement dynamics. Furthermore, we map out the phonon distributions throughout the action of the displacement force. Our investigation shows corrections t…

Driven Appearance and Disappearance of Quantum Zeno Effect in the Dynamics of a Four-level Trapped Ion

2001

An example of constrained unitary quantum dynamics in the context of trapped ions is given. We study a laser driven four-level ion system confined in an isotropic three-dimensional Paul microtrap. Our main result is that when two independent controllable continuous measurement processes are simultaneously present, the unitary quantum dynamics of the system can be parametrically frozen into a one-dimensional Hilbert subspace (Quantum Zeno Effect) or constrained into a two-dimensional one, at will. Conditions under which one of the two processes acts upon the physical system inhibiting the effects due to the other one, are explicitly found and discussed (Hierarchically Controlled Dynamics).

Quantum Computing Experiments with Cold Trapped Ions

2016

Entanglement replication in driven-dissipative many body systems

2012

We study the dissipative dynamics of two independent arrays of many-body systems, locally driven by a common entangled field. We show that in the steady state the entanglement of the driving field is reproduced in an arbitrarily large series of inter-array entangled pairs over all distances. Local nonclassical driving thus realizes a scale-free entanglement replication and long-distance entanglement distribution mechanism that has immediate bearing on the implementation of quantum communication networks.