25 research outputs found
Realizing quantum gates with optically-addressable Yb ion qudits
The use of multilevel information carriers, also known as qudits, is a
promising path for exploring scalability of quantum computing devices. In this
work, we present a proof-of-principle realization of a quantum processor that
uses optically-addressed Yb ion qudits in a linear trap. The rich
level structure of Yb ions makes it possible to use the Zeeman
sublevels of the quadrupole clock transition at 435.5 nm for efficient and
robust qudit encoding. We demonstrate the realization of the universal set of
gates consisting of single-qudit rotations and two-qudit entangling operation
with a two-ququart system, which is formally equivalent to a universal
gate-based four-qubit processor. Our results paves a way towards further
studies of more efficient implementations of quantum algorithms with
trapped-ion-based processors.Comment: 9 pages, 3 figure
Demonstration of a parity-time symmetry breaking phase transition using superconducting and trapped-ion qutrits
Scalable quantum computers hold the promise to solve hard computational
problems, such as prime factorization, combinatorial optimization, simulation
of many-body physics, and quantum chemistry. While being key to understanding
many real-world phenomena, simulation of non-conservative quantum dynamics
presents a challenge for unitary quantum computation. In this work, we focus on
simulating non-unitary parity-time symmetric systems, which exhibit a
distinctive symmetry-breaking phase transition as well as other unique features
that have no counterpart in closed systems. We show that a qutrit, a
three-level quantum system, is capable of realizing this non-equilibrium phase
transition. By using two physical platforms - an array of trapped ions and a
superconducting transmon - and by controlling their three energy levels in a
digital manner, we experimentally simulate the parity-time symmetry-breaking
phase transition. Our results indicate the potential advantage of multi-level
(qudit) processors in simulating physical effects, where additional accessible
levels can play the role of a controlled environment.Comment: 14 pages, 9 figure
The ATLAS Transition Radiation Tracker (TRT) proportional drift tube: design and performance
A straw proportional counter is the basic element of the ATLAS Transition Radiation Tracker (TRT). Its detailed properties as well as the main properties of a few TRT operating gas mixtures are described. Particular attention is paid to straw tube performance in high radiation conditions and to its operational stability
The ATLAS TRT electronics
The ATLAS inner detector consists of three sub-systems: the pixel detector spanning the radius range 4cm-20cm, the semiconductor tracker at radii from 30 to 52 cm, and the transition radiation tracker (TRT), tracking from 56 to 107 cm. The TRT provides a combination of continuous tracking with many projective measurements based on individual drift tubes (or straws) and of electron identification based on transition radiation from fibres or foils interleaved between the straws themselves. This paper describes the on and off detector electronics for the TRT as well as the TRT portion of the data acquisition (DAQ) system
Creutzfeldt–Jakob disease in the Republic of Sakha (Yakutia)
Creutzfeldt–Jakob disease (CJD) is a rare neurodegenerative disease caused by the accumulation of the pathological isoform of prion protein. The classic clinical presentation of CJD is characterized by rapidly progressive dementia, ataxia, myoclonus, and akinetic mutism at the terminal stage of the disease. Of the instrumental techniques, brain magnetic resonance imaging plays a leading role in clinical practice. The authors followed up 4 patients with probable CJD in the Republic of Sakha (Yakutia) in 2014 to 2019. All the patients had approximately the same age (50–60 years) at disease onset and onset with non-specific cerebral symptoms. However, the subsequent development of rapidly progressive dementia and other characteristic features might suggest CJD. The patients were found to have characteristic neuroimaging signs as hyperintensity of the caudate nuclei and pulvinars in the fluid-attenuated inversion recovery (FLAIR) and diffusion weighted imaging (DWI) modes to form the typical signal of hockey sticks, as well as hyperintensity of the gray matter in the DWI mode (the symptom of the «Venus necklace»). In 3 patients, the disease ended fatally within a year of its onset. The fourth patient with a disease duration of 6 months is being supervised at home. The authors reason that the diagnosis of CJD is now insufficient due to the similarity of its clinical symptoms at the onset with other disorders, including cerebrovascular and neurodegenerative diseases
Continuous dynamical decoupling of optical Yb qudits with radiofrequency fields
The use of multilevel quantum information carriers, also known as qudits,
attracts a significant deal of interest as a way for further scalability of
quantum computing devices. However, a nontrivial task is to experimentally
achieve a gain in the efficiency of realizing quantum algorithms with qudits
since higher qudit levels typically have relatively short coherence times
compared to qubit states. Here we propose and experimentally demonstrate two
approaches for the realization of continuous dynamical decoupling of
magnetic-sensitive states with for qudits encoded in optical
transition of trapped Yb ions. We achieve improvement in qudit
levels coherence time by the order of magnitude (more than 9 ms) without any
magnetic shielding, which reveals the potential advantage of the symmetry of
the Yb ion energy structure for counteracting the magnetic field
noise. Our results are a step towards the realization of qudit-based algorithms
using trapped ions.Comment: 12 pages, 5 figure