30 research outputs found
Controllability and universal three-qubit quantum computation with trapped electron states
We show how to control and perform universal three-qubit quantum computation
with trapped electron quantum states. The three qubits are the electron spin,
and the first two quantum states of the cyclotron and axial harmonic
oscillators. We explicitly show how the universal gates can be performed. As an
example of a non-trivial quantum algorithm, we outline the implementation of
the Deutsch-Jozsa algorithm in this system.Comment: 4 pages, 1 figure. Typos corrected. The original publication is
available at http://www.springerlink.co
Optimized Planar Penning Traps for Quantum Information Studies
A one-electron qubit would offer a new option for quantum information
science, including the possibility of extremely long coherence times.
One-quantum cyclotron transitions and spin flips have been observed for a
single electron in a cylindrical Penning trap. However, an electron suspended
in a planar Penning trap is a more promising building block for the array of
coupled qubits needed for quantum information studies. The optimized design
configurations identified here promise to make it possible to realize the
elusive goal of one trapped electron in a planar Penning trap for the first
time - a substantial step toward a one-electron qubit
From a single- to a double-well Penning trap
The new generation of planar Penning traps promises to be a flexible and
versatile tool for quantum information studies. Here, we propose a fully
controllable and reversible way to change the typical trapping harmonic
potential into a double-well potential, in the axial direction. In this
configuration a trapped particle can perform coherent oscillations between the
two wells. The tunneling rate, which depends on the barrier height and width,
can be adjusted at will by varying the potential difference applied to the trap
electrodes. Most notably, tunneling rates in the range of kHz are achievable
even with a trap size of the order of 100 microns.Comment: 4 pages, 7 figure
Spin chains with electrons in Penning traps
We demonstrate that spin chains are experimentally feasible using electrons
confined in micro-Penning traps, supplemented with local magnetic field
gradients. The resulting Heisenberg-like system is characterized by coupling
strengths showing a dipolar decay. These spin chains can be used as a channel
for short distance quantum communication. Our scheme offers high accuracy in
reproducing an effective spin chain with relatively large transmission rate.Comment: 21 pages, 1 figure, accepted for publication in PR
Trapped electrons in vacuum for a scalable quantum processor
We describe in detail a theoretical scheme to trap and manipulate an arbitrary number of electrons in vacuum for universal quantum computation. The particles are confined in a linear array of Penning traps by means of a combination of static electric and magnetic fields. Two-electron operations are realized by controlling the Coulomb interaction between neighboring particles. The performances of such a device are evaluated in terms of clock speed, fidelity, and decoherence rates
Quantum spin models with electrons in Penning traps
We propose a scheme to engineer an effective spin Hamiltonian starting from a
system of electrons confined in micro-Penning traps. By means of appropriate
sequences of electromagnetic pulses, alternated to periods of free evolution,
we control the shape and strength of the spin-spin interaction. Moreover, we
can modify the effective magnetic field experienced by the particle spin. This
procedure enables us to reproduce notable quantum spin systems, such as Ising
and XY models. Thanks to its scalability, our scheme can be applied to a fairly
large number of trapped particles within the reach of near future technology.Comment: 22 pages, 1 figure, added minor changes and typos, accepted for
publication in PR
Array of planar Penning traps as a nuclear magnetic resonance molecule for quantum computation
An array of planar Penning traps, holding single electrons, can realize an artificial molecule suitable for NMR-like quantum-information processing. The effective spin-spin coupling is accomplished by applying a magnetic field gradient, combined to the Coulomb interaction acting between the charged particles. The system lends itself to scalability, since the same substrate can easily accommodate an arbitrary number of traps. Moreover, the coupling strength is tunable and under experimental control. Our theoretical predictions take into account a realistic setting, within the reach of current technology
Performance of a deterministic source of entangled photonic qubits
We study the possible limitations and sources of decoherence in the scheme
for the deterministic generation of polarization-entangled photons, recently
proposed by Gheri et al. [K. M. Gheri et al., Phys. Rev. A 58, R2627 (1998)],
based on an appropriately driven single atom trapped within an optical cavity.
We consider in particular the effects of laser intensity fluctuations, photon
losses, and atomic motion.Comment: 10 pages, 6 figure
Creation and manipulation of entanglement in spin chains far from equilibrium
We investigate creation, manipulation, and steering of entanglement in spin
chains from the viewpoint of quantum communication between distant parties. We
demonstrate how global parametric driving of the spin-spin coupling and/or
local time-dependent Zeeman fields produce a large amount of entanglement
between the first and the last spin of the chain. This occurs whenever the
driving frequency meets a resonance condition, identified as "entanglement
resonance". Our approach marks a promising step towards an efficient quantum
state transfer or teleportation in solid state system. Following the reasoning
of Zueco et al. [1], we propose generation and routing of multipartite
entangled states by use of symmetric tree-like structures of spin chains.
Furthermore, we study the effect of decoherence on the resulting spin
entanglement between the corresponding terminal spins.Comment: 10 pages, 8 figure
Trapped electron coupled to superconducting devices
We propose to couple a trapped single electron to superconducting structures
located at a variable distance from the electron. The electron is captured in a
cryogenic Penning trap using electric fields and a static magnetic field in the
Tesla range. Measurements on the electron will allow investigating the
properties of the superconductor such as vortex structure, damping and
decoherence. We propose to couple a superconducting microwave resonator to the
electron in order to realize a circuit QED-like experiment, as well as to
couple superconducting Josephson junctions or superconducting quantum
interferometers (SQUIDs) to the electron. The electron may also be coupled to a
vortex which is situated in a double well potential, realized by nearby pinning
centers in the superconductor, acting as a quantum mechanical two level system
that can be controlled by a transport current tilting the double well
potential. When the vortex is trapped in the interferometer arms of a SQUID,
this would allow its detection both by the SQUID and by the electron.Comment: 13 pages, 5 figure