41 research outputs found
Energy Transport in Trapped Ion Chains
We experimentally study energy transport in chains of trapped ions. We use a
pulsed excitation scheme to rapidly add energy to the local motional mode of
one of the ions in the chain. Subsequent energy readout allows us to determine
how the excitation has propagated throughout the chain. We observe energy
revivals that persist for many cycles. We study the behavior with an increasing
number of ions of up to 37 in the chain, including a zig-zag configuration. The
experimental results agree well with the theory of normal mode evolution. The
described system provides an experimental toolbox for the study of
thermodynamics of closed systems and energy transport in both classical and
quantum regimes
Universal quantum computation in decoherence-free subspaces with hot trapped-ions
We consider interactions that generate a universal set of quantum gates on
logical qubits encoded in a collective-dephasing-free subspace, and discuss
their implementations with trapped ions. This allows for the removal of the
by-far largest source of decoherence in current trapped-ion experiments,
collective dephasing. In addition, an explicit parametrization of all two-body
Hamiltonians able to generate such gates without the system's state ever
exiting the protected subspace is provided.Comment: 8 pages, 1 figur
Polarization of electric field noise near metallic surfaces
Electric field noise in proximity to metallic surfaces is a poorly understood
phenomenon that appears in different areas of physics. Trapped ion quantum
information processors are particular susceptible to this noise, leading to
motional decoherence which ultimately limits the fidelity of quantum
operations. On the other hand they present an ideal tool to study this effect,
opening new possibilities in surface science. In this work we analyze and
measure the polarization of the noise field in a micro-fabricated ion trap for
various noise sources. We find that technical noise sources and noise emanating
directly from the surface give rise to different degrees of polarization which
allows us to differentiate between the two noise sources. Based on this, we
demonstrate a method to infer the magnitude of surface noise in the presence of
technical noise
Two mode coupling in a single ion oscillator via parametric resonance
Atomic ions, confined in radio-frequency Paul ion traps, are a promising
candidate to host a future quantum information processor. In this letter, we
demonstrate a method to couple two motional modes of a single trapped ion,
where the coupling mechanism is based on applying electric fields rather than
coupling the ion's motion to a light field. This reduces the design constraints
on the experimental apparatus considerably. As an application of this
mechanism, we cool a motional mode close to its ground state without accessing
it optically. As a next step, we apply this technique to measure the mode's
heating rate, a crucial parameter determining the trap quality. In principle,
this method can be used to realize a two-mode quantum parametric amplifier.Comment: 8 pages, 5 figure
Materials Challenges for Trapped-Ion Quantum Computers
Trapped-ion quantum information processors store information in atomic ions
maintained in position in free space via electric fields. Quantum logic is
enacted via manipulation of the ions' internal and shared motional quantum
states using optical and microwave signals. While trapped ions show great
promise for quantum-enhanced computation, sensing, and communication, materials
research is needed to design traps that allow for improved performance by means
of integration of system components, including optics and electronics for
ion-qubit control, while minimizing the near-ubiquitous electric-field noise
produced by trap-electrode surfaces. In this review, we consider the materials
requirements for such integrated systems, with a focus on problems that hinder
current progress toward practical quantum computation. We give suggestions for
how materials scientists and trapped-ion technologists can work together to
develop materials-based integration and noise-mitigation strategies to enable
the next generation of trapped-ion quantum computers.Comment: 19 pages, 7 figures, commments welcome, now with all the figure