# All

The Sending-or-Not-Sending protocol of the twin-field quantum key

distribution (TF-QKD) has its advantage of unconditional security proof under

any coherent attack and fault tolerance to large misalignment error. So far

this is the only coherent-state based TF-QKD protocol that has considered

finite-key effect, the statistical fluctuations. Here we consider the complete

finite-key effects for the protocol and we show by numerical simulation that

the protocol with typical finite number of pulses in practice can produce

Shannon entropy ($S$), Fisher information ($I$) and a measure equivalent to

Fisher-Shannon complexity $(C_{IS})$ of a ro-vibrational state of diatomic

molecules (O$_2$, O$_2^+$, NO, NO$^+$) with generalized Kratzer potential is

analyzed.

Atomically-thin layers of two-dimensional materials can be assembled in

vertical stacks held together by relatively weak van der Waals forces, allowing

for coupling between monolayer crystals with incommensurate lattices and

arbitrary mutual rotation. A profound consequence of using these degrees of

freedom is the emergence of an overarching periodicity in the local atomic

registry of the constituent crystal structures, known as a moir\'e

superlattice. Its presence in graphene/hexagonal boron nitride (hBN) structures

A quantum error correction (QEC) code uses $N_{\rm c}$ quantum bits to

construct one "logical" quantum bits of better quality than the original

"physical" ones. QEC theory predicts that the failure probability $p_L$ of

logical qubits decreases exponentially with $N_{\rm c}$ provided the failure

probability $p$ of the physical qubit is below a certain threshold $p<p_{\rm

th}$. In particular QEC theorems imply that the logical qubits can be made

arbitrarily precise by simply increasing $N_{\rm c}$. In this letter, we search

We study the computational complexity of quantum-mechanical expectation

values of single-particle operators in bosonic and fermionic multi-particle

product states. Such expectation values appear, in particular, in

full-counting-statistics problems. Depending on the initial multi-product

state, the expectation values may be either easy to compute (the required

number of operations scales polynomially with the particle number) or hard to

compute (at least as hard as a permanent of a matrix). However, if we only

There have been several research works on the hidden shift problem, quantum

algorithms for the problem, and their applications. However, all the results

have focused on discrete groups. So, we define a continuous hidden shift

problem on $\mathbb{R}^n$ as an extension of the hidden shift problem, and

construct a quantum computing algorithm for solving this problem efficiently.

We consider a setting where qubits are processed sequentially, and derive

fundamental limits on the rate at which classical information can be

transmitted using quantum states that decohere in time. Specifically, we model

the sequential processing of qubits using a single server queue, and derive

explicit expressions for the capacity of such a `queue-channel.' We also

demonstrate a sweet-spot phenomenon with respect to the arrival rate to the

queue, i.e., we show that there exists a value of the arrival rate of the

Information-based uncertainty measures like Shannon entropy, Onicescu energy

and Fisher information (in position and momentum space) are employed to

understand the effect of \emph{symmetric and asymmetric} confinement in a

quantum harmonic oscillator. Also, the transformation of Hamiltonian into a

dimensionless form gives an idea of the composite effect of force constant and

confinement length ($x_c$). In symmetric case, a wide range of $x_{c}$ has been

taken up, whereas asymmetric confinement is dealt by shifting the minimum of

In order to verify the results of Boson sampling experiments one must be able

to compute the permanent of the associated Hamiltonians. Here we first present

a freely available software package, available in both serial and parallel

versions. As part of the timing runs for this package we set a new world

recored for the matrix order on which a permanent has been computed. We include

specialised functions for matrices of limited bandwidth, which also demonstrate

Starting from the many-body Schr\"odinger equation, we derive a new type of

Lindblad Master equations describing a cyclic exciton/electron dynamics in the

light harvesting complex and the reaction center. These equations resemble the

Master equations for the electric current in mesoscopic systems, and they go

beyond the single-exciton description by accounting for the multi-exciton

states accumulated in the antenna, as well as the charge-separation,

fluorescence and photo-absorption. Although these effects take place on very