Artificial neural network, consisting of many neurons in different layers, is

an important method to simulate humain brain. Usually, one neuron has two

operations: one is linear, the other is nonlinear. The linear operation is

inner product and the nonlinear operation is represented by an activation

function. In this work, we introduce a kind of quantum neuron whose inputs and

outputs are quantum states. The inner product and activation operator of the

quantum neurons can be realized by quantum circuits. Based on the quantum

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In this work, we provide a strengthening of the data processing inequality

for the relative entropy introduced by Belavkin and Staszewski (BS-entropy).

This extends previous results by Carlen and Vershynina for the relative entropy

and other standard $f$-divergences. To this end, we provide two new equivalent

conditions for the equality case of the data processing inequality for the

BS-entropy. Subsequently, we extend our result to a larger class of maximal

Author(s): Nathan Ng and Michael Kolodrubetz

We consider a many-body localized system coupled globally to a central $d$-level system. Under an appropriate scaling of $d$ and $L$, we find evidence that the localized phase survives. We argue for two possible thermalizing phases, depending on whether the qudit becomes fully ergodic. This system p...

[Phys. Rev. Lett. 122, 240402] Published Wed Jun 19, 2019

Author(s): Anupama Unnikrishnan, Ian J. MacFarlane, Richard Yi, Eleni Diamanti, Damian Markham, and Iordanis Kerenidis

Quantum communication networks have the potential to revolutionize information and communication technologies. Here we are interested in a fundamental property and formidable challenge for any communication network, that of guaranteeing the anonymity of a sender and a receiver when a message is tran...

[Phys. Rev. Lett. 122, 240501] Published Wed Jun 19, 2019

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Author(s): Rogério J. de Assis, Taysa M. de Mendonça, Celso J. Villas-Boas, Alexandre M. de Souza, Roberto S. Sarthour, Ivan S. Oliveira, and Norton G. de Almeida

We perform an experiment in which a quantum heat engine works under two reservoirs, one at a positive spin temperature and the other at an effective negative spin temperature, i.e., when the spin system presents population inversion. We show that the efficiency of this engine can be greater than tha...

[Phys. Rev. Lett. 122, 240602] Published Wed Jun 19, 2019

We quantitatively assess the energetic cost of several well-known control

protocols that achieve a finite time adiabatic dynamics, namely counterdiabatic

and local counterdiabatic driving, optimal control, and inverse engineering. By

employing a cost measure based on the norm of the total driving Hamiltonian, we

show that a hierarchy of costs emerges that is dependent on the protocol

duration. As case studies we explore the Landau-Zener model, the quantum

harmonic oscillator, and the Jaynes-Cummings model and establish that

We propose and demonstrate a polarization-based truncated SU(1,1)

interferometer that outputs the desired optical joint-quadrature of a two-mode

squeezed vacuum field and allows its measurements using a single balanced

homodyne detector. Using such setup we demonstrated up to $\approx$2 dB of

quantum noise suppression below the shot-noise limit in intensity-difference

and phase-sum joint quadratures, and confirmed entanglement between the two

quantum fields. Our proposed technique results in a better balance between the

A fundamental aspect of the quantum-to-classical limit is the transition from

a non-commutative algebra of observables to commutative one. However, this

transition is not possible if we only consider unitary evolutions. One way to

describe this transition is to consider the Gamow vectors, which introduce

exponential decays in the evolution. In this paper, we give two mathematical

models in which this transition happens in the infite time limit. In the first

As known all physical properties of solids are described well by the system

of quantum linear harmonic oscillators. It is shown in the present paper that

the system consisting of classical linear harmonic oscillators having

temperature dependent masses or (and) frequencies has the same partition

function as the system consisting of quantum linear harmonic oscillators having

temperature independent masses and frequencies while the means of the square

displacements of the positions of the oscillators from their mean positions for

Let V be a symplectic vector space and let $\mu$ be the oscillator

representation of Sp(V). It is natural to ask how the tensor power

representation $\mu^{\otimes t}$ decomposes. If V is a real vector space, then

Howe duality asserts that there is a one-one correspondence between the

irreducible subrepresentations of Sp(V) and the irreps of an orthogonal group

O(t). It is well-known that this duality fails over finite fields. Addressing

this situation, Gurevich and Howe have recently assigned a notion of rank to