56 research outputs found
Electro-optical ion trap for experiments with atom-ion quantum hybrid systems
In the development of atomic, molecular and optical (AMO) physics, atom-ion
hybrid systems are characterized by the presence of a new tool in the
experimental AMO toolbox: atom-ion interactions. One of the main limitations in
state-of-the-art atom-ion experiments is represented by the micromotion
component of the ions' dynamics in a Paul trap, as the presence of micromotion
in atom-ion collisions results in a heating mechanism that prevents atom-ion
mixtures from undergoing a coherent evolution. Here we report the design and
the simulation of a novel ion trapping setup especially conceived for the
integration with an ultracold atoms experiment. The ion confinement is realized
by using an electro-optical trap based on the combination of an optical and an
electrostatic field, so that no micromotion component will be present in the
ions' dynamics. The confining optical field is generated by a deep optical
lattice created at the crossing of a bow-tie cavity, while a static electric
quadrupole ensures the ions' confinement in the plane orthogonal to the optical
lattice. The setup is also equipped with a Paul trap for cooling the ions
produced by photoionization of a hot atomic beam, and the design of the two ion
traps facilitates the swapping of the ions from the Paul trap to the
electro-optical trap.Comment: 17 pages, 8 figure
A scalable hardware and software control apparatus for experiments with hybrid quantum systems
Modern experiments with fundamental quantum systems - like ultracold atoms,
trapped ions, single photons - are managed by a control system formed by a
number of input/output electronic channels governed by a computer. In hybrid
quantum systems, where two or more quantum systems are combined and made to
interact, establishing an efficient control system is particularly challenging
due to the higher complexity, especially when each single quantum system is
characterized by a different timescale. Here we present a new control apparatus
specifically designed to efficiently manage hybrid quantum systems. The
apparatus is formed by a network of fast communicating Field Programmable Gate
Arrays (FPGAs), the action of which is administrated by a software. Both
hardware and software share the same tree-like structure, which ensures a full
scalability of the control apparatus. In the hardware, a master board acts on a
number of slave boards, each of which is equipped with an FPGA that locally
drives analog and digital input/output channels and radiofrequency (RF) outputs
up to 400 MHz. The software is designed to be a general platform for managing
both commercial and home-made instruments in a user-friendly and intuitive
Graphical User Interface (GUI). The architecture ensures that complex control
protocols can be carried out, such as performing of concurrent commands loops
by acting on different channels, the generation of multi-variable error
functions and the implementation of self-optimization procedures. Although
designed for managing experiments with hybrid quantum systems, in particular
with atom-ion mixtures, this control apparatus can in principle be used in any
experiment in atomic, molecular, and optical physics.Comment: 10 pages, 12 figure
An Aharonov-Bohm interferometer for determining Bloch band topology
The geometric structure of an energy band in a solid is fundamental for a
wide range of many-body phenomena in condensed matter and is uniquely
characterized by the distribution of Berry curvature over the Brillouin zone.
In analogy to an Aharonov-Bohm interferometer that measures the magnetic flux
penetrating a given area in real space, we realize an atomic interferometer to
measure Berry flux in momentum space. We demonstrate the interferometer for a
graphene-type hexagonal lattice, where it has allowed us to directly detect the
singular Berry flux localized at each Dirac point. We show that the
interferometer enables one to determine the distribution of Berry curvature
with high momentum resolution. Our work forms the basis for a general framework
to fully characterize topological band structures and can also facilitate
holonomic quantum computing through controlled exploitation of the geometry of
Hilbert space.Comment: 5+5 page
Design of a Littrow-type diode laser with independent control of cavity length and grating rotation
We present a novel, to the best of our knowledge, extended-cavity diode laser based on a modified Littrow configuration. The coarse wavelength adjustment via the rotation of a diffraction grating is decoupled from the fine tuning of the external cavity modes by positioning a piezo transducer behind the diode laser, making the laser robust against misalignment and hysteresis even with long external cavities. Two laser prototypes with external cavities of different lengths were tested with a 780 nm laser diode, and locked to an atomic reference. We observed a mode-hop-free frequency tunability broader than the free spectral range of the external cavity upon changes in its length. The design is well suited to atomic and molecular experiments demanding a high level of stability over time
Orientational Melting in a Mesoscopic System of Charged Particles
: A mesoscopic system of a few particles can undergo changes of configuration that resemble phase transitions but with a nonuniversal behavior. A notable example is orientational melting, in which localized particles with long-range repulsive interactions forming a two-dimensional crystal become delocalized in common closed trajectories. Here we report the observation of orientational melting occurring in a two-dimensional crystal of up to 15 ions. We measure density-density correlations to quantitatively characterize the occurrence of melting, and use a Monte Carlo simulation to extract the angular kinetic energy of the ions. By adding a pinning impurity, we demonstrate the nonuniversality of orientational melting and create novel configurations in which localized and delocalized particles coexist. Our system realizes an experimental testbed for studying changes of configurations in two-dimensional mesoscopic systems, and our results pave the way for the study of quantum phenomena in ensembles of delocalized ions
A compact radiofrequency drive based on interdependent resonant circuits for precise control of ion traps
Paul traps are widely used to confine electrically charged particles like
atomic and molecular ions by using an intense radiofrequency (RF) field,
typically obtained by a voltage drop on capacitative electrodes placed in
vacuum. We present a RF drive realized on a compact printed circuit board (PCB)
and providing a high-voltage RF signal to a quadrupole Paul trap. The circuit
is formed by four interdependent resonant circuits each of which connected
to an electrode of a Paul trap fed by low-noise amplifiers, leading to an
output voltage of peak-to-peak amplitude up to 200 V at 3.23 MHz. The presence
of a single resonant circuit for each electrode ensures a strong control on the
voltage drop on each electrode, e.g. by applying a DC field through a bias tee.
Additionally, the moderate quality factor Q = 67 of the resonant circuits
ensures a fast operation of the drive, which can be turned on and off in less
than 10 s. Finally, the RF lines are equipped with pick-ups that sample
the RF in phase and amplitude, thus providing a signal that can be used to
actively control the voltage drop at the trap's electrodes. Thanks to its
features, this drive is particularly suited for experiments in which high trap
stability and excellent micromotion compensation are required.Comment: 7 pages, 8 figure
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