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

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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.