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We discuss the rotational cooling of diatomic molecules in a Bose-Einstein
condensate (BEC) of ultra-cold atoms by emission of phonons with orbital
angular momentum. Despite the superfluidity of the BEC there is no frictionless
rotation for typical molecules since the dominant cooling occurs via emission
of particle-like phonons. Only for macro-dimers, whose size becomes comparable
or larger than the condensate healing length, a Landau-like, critical angular

The No Low-Energy Trivial States (NLTS) conjecture of Freedman and Hastings
(Quantum Information and Computation 2014), which asserts the existence of
local Hamiltonians whose low energy states cannot be generated by constant
depth quantum circuits, identifies a fundamental obstacle to resolving the
quantum PCP conjecture. Progress towards the NLTS conjecture was made by Eldar
and Harrow (Foundations of Computer Science 2017), who proved a closely related

The multichannel Na-Cs interactions are characterized by a series of
measurements using two atoms in an optical tweezer, along with a multichannel
quantum defect theory (MQDT). The triplet and singlet scattering lengths are
measured by performing Raman spectroscopy of the Na-Cs motional states and
least-bound molecular state in the tweezer. Magnetic Feshbach resonances are
observed for only two atoms at fields which agree well with the MQDT. Our
methodology, which promotes the idea of an effective theory of interaction, can

We report, in a sequence of notes, our work on the Alibaba Cloud Quantum
Development Kit (AC-QDK). AC-QDK provides a set of tools for aiding the
development of both quantum computing algorithms and quantum processors, and is
powered by a large-scale classical simulator deployed on Alibaba Cloud. In this
note, we report the computational experiments demonstrating the classical
simulation capability of AC-QDK. We use as a benchmark the random quantum
circuits designed for Google's Bristlecone QPU {\cite{GRCS}}. We simulate

We investigate theoretically the dynamics of two quasi-degenerate orthogonal
mechanical modes of a suspended nanowire coupled to the two-level system of a
single-fluorescent molecule by Stark effect. We show that by driving the
molecular two-level system with a laser field one can engineer the effective
mechanical spectrum leading to an exceptional degeneracy point where the two
mechanical modes coalesce. It allows the topological actuation of the modes by

Quantum error correction protocols will play a central role in the
realisation of quantum computing; the choice of error correction code will
influence the full quantum computing stack, from the layout of qubits at the
physical level to gate compilation strategies at the software level. As such,
familiarity with quantum coding is an essential prerequisite for the
understanding of current and future quantum computing architectures. In this
review, we provide an introductory guide to the theory and implementation of

We propose a protocol for sympathetically cooling neutral atoms without
destroying the quantum information stored in their internal states. This is
achieved by designing state-insensitive Rydberg interactions between the
data-carrying atoms and cold auxiliary atoms. This can be used to extend the
lifetime of quantum storage based on neutral atoms and can have applications
for long quantum computations. The protocol can also be modified to realize
state-insensitive interactions between the data and the auxiliary atoms but

The increasing complexity of engineered quantum systems and devices raises
the need for efficient methods to verify that these systems are indeed
performing the desired quantum dynamics. Due to the inevitable coupling to
external environments, these methods should obtain not only the unitary part of
the dynamics, but also the dissipation and decoherence affecting the system's
dynamics. Here, we propose a method for reconstructing the Lindbladian
governing the Markovian dynamics of open many-body quantum systems, using data

We have studied the effect of a non-Hermitian Bosonic bath on the dynamics of
a two-level spin system. The non-Hermitian Hamiltonian of the bath is chosen
such that it converges to the harmonic oscillator Hamiltonian when the
non-Hermiticity is switched off. We calculate the dynamics of the spin system
and found that the non-Hermiticity can have positive as well as negative
effects on the coherence of the system. However, the decoherence can be
completely eliminated by choosing the non-Hermiticity parameter and the phase

The paper retraces the development from the measurement problem to the
primitive ontology programme. It assesses the contribution of the GRW theory to
this programme and discusses the pros and cons of the GRWm matter density
ontology and the GRWf flash ontology in comparison to the Bohmian particle
ontology. It thereby pursues the evaluation of the proposals for a primitive
ontology of quantum physics.

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