2 research outputs found
Continuous variable direct secure quantum communication using Gaussian states
Continuous variable one-way and controlled-two-way secure direct quantum
communication schemes have been designed using Gaussian states. Specifically, a
scheme for continuous variable quantum secure direct communication and another
scheme for continuous variable controlled quantum dialogue are proposed using
single-mode squeezed coherent states. The security of the proposed schemes
against a set of attacks (e.g., Gaussian quantum cloning machine and intercept
resend attacks) has been proved. Further, it is established that the proposed
schemes do not require two-mode squeezed states which are essential for a set
of existing proposals. The controlled two-way communication scheme is shown to
be very general in nature as it can be reduced to schemes for various
relatively simpler cryptographic tasks like controlled deterministic secure
communication, quantum dialogue, quantum key distribution. In addition, it is
briefly discussed that the proposed schemes can provide us tools to design
quantum cryptographic solutions for several socioeconomic problems.Comment: Continuous Variable protocols are designed for one-way and
controlled-two-way secure direct quantum communication using single-mode
squeezed coherent state
Temperature-anisotropy conjugate magnon squeezing in antiferromagnets
Quantum squeezing is an essential asset in the field of quantum science and
technology. In this study, we investigate the impact of temperature and
anisotropy on squeezing of quantum fluctuations in two-mode magnon states
within uniaxial antiferromagnetic materials. Through our analysis, we discover
that the inherent nonlinearity in these bipartite magnon systems gives rise to
a conjugate magnon squeezing effect across all energy eigenbasis states, driven
by temperature and anisotropy. We show that temperature induces amplitude
squeezing, whereas anisotropy leads to phase squeezing. In addition, we observe
that the two-mode squeezing characteristic of magnon eigenenergy states is
associated with amplitude squeezing. This highlights the constructive impact of
temperature and the destructive impact of anisotropy on two-mode magnon
squeezing. Nonetheless, our analysis shows that the destructive effect of
anisotropy is bounded. We demonstrate this by showing that, at a given
temperature, the squeezing of the momentum (phase) quadrature (or equivalently,
the stretching of the position (amplitude) quadrature) approaches a constant
function of anisotropy after a finite value of anisotropy. Moreover, our study
demonstrates that higher magnon squeeze factors can be achieved at higher
temperatures, smaller levels of anisotropy, and closer to the Brillouin zone
center. All these characteristics are specific to low-energy magnons in the
uniaxial antiferromagnetic materials that we examine here