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Quantum secure signature schemes have a lot of attention recently, in

particular because of the NIST call to standardize quantum safe cryptography.

However, only few signature schemes can have concrete quantum security because

of technical difficulties associated with the Quantum Random Oracle Model

(QROM). In this paper, we show that code-based signature schemes based on the

full domain hash paradigm can behave very well in the QROM i.e. that we can

have tight security reductions. We also study quantum algorithms related to the

The fundamental physical description of Nature is based on two mutually

incompatible theories: Quantum Mechanics and General Relativity. Their

unification in a theory of Quantum Gravity (QG) remains one of the main

challenges of theoretical physics. Quantum Gravity Phenomenology (QGP) studies

QG effects in low-energy systems. The basis of one such phenomenological model

is the Generalized Uncertainty Principle (GUP), which is a modified Heisenberg

uncertainty relation and predicts a deformed canon ical commutator. In this

We present a new optical scheme for BB84 protocol quantum key distribution

(QKD). The proposed setup consists of a compact all-fiber polarization encoding

optical scheme based on LiNbO3 phase modulators, single laser source and two

single-photon detectors. Optical scheme consists of standard telecommunication

components and is suitable for both fiber and free-space quantum communication

channels. Low losses (~2dB) in Bob's device increase both the key generation

We study the underlying mechanism in the implementation of unitary control on

a system with an experimental apparatus. We regard the unitary time-evolution

in the system as a physical phenomenon that results from the interaction

between the system and the apparatus. We model this situation using the setup

of the system and an external system that represents the apparatus. We consider

the conditions required to approximate the dynamics of the reduced density

Fundamental questions in chemistry and physics may never be answered due to

the exponential complexity of the underlying quantum phenomena. A desire to

overcome this challenge has sparked a new industry of quantum technologies with

the promise that engineered quantum systems can address these hard problems. A

key step towards demonstrating such a system will be performing a computation

beyond the capabilities of any classical computer, achieving so-called quantum

A strong electromagnetic field interacting with an electron system generates

both the Rabi oscillations and the Stark splitting of the electron density.

Changing of the electron density gives rise to nonadiabatic effects due to

existence of the electron-vibrational interaction in a dissipative system. In

this Letter, the mechanism of energy transfer between the electron system and

the phonon reservoir is presented. This mechanism is based on establishment of

What are the conditions for adiabatic quantum computation (AQC) to outperform

classical computation? Although there exist several quantum adiabatic

algorithms achieving the strong quantum speedup, the essential keys to their

speedups are still unclear. Here, we investigate the connection between

superpositions of macroscopically distinct states and known examples of the

speedup in AQC. To formalize this notion we consider an index $p$ that

quantifies a superposition of macroscopically distinct states from the

We investigate the electric quadrupole interaction of an alkali-metal atom

with guided light in the fundamental and higher-order modes of a vacuum-clad

ultrathin optical fiber. We calculate the quadrupole Rabi frequency, the

quadrupole oscillator strength, and their enhancement factors. In the example

of a rubidium-87 atom, we study the dependencies of the quadrupole Rabi

frequency on the quantum numbers of the transition, the mode type, the phase

circulation direction, the propagation direction, the orientation of the

Quantum bits based on individual trapped atomic ions constitute a promising

technology for building a quantum computer, with all the elementary operations

having been achieved with the necessary precision. However, the essential

two-qubit logic gate used for generating quantum entanglement has hitherto

always been performed in an adiabatic regime, where the gate is slow compared

with the characteristic motional frequencies of ions in the trap, giving logic

- Read more about Fast quantum logic gates with trapped-ion qubits. (arXiv:1709.06952v1 [quant-ph])
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We introduce and analyze graph-associated entanglement cost, a generalization

of the entanglement cost of quantum states to multipartite settings. We

identify a necessary and sufficient condition for any multipartite entangled

state to be constructible when quantum communication between the multiple

parties is restricted to a quantum network represented by a tree. The condition

for exact state construction is expressed in terms of the Schmidt ranks of the

state defined with respect to edges of the tree. We also study approximate