Author(s): Pietro Liuzzo-Scorpo, Andrea Mari, Vittorio Giovannetti, and Gerardo Adesso
Given a certain amount of entanglement available as a resource, what is the most efficient way to accomplish a quantum task? We address this question in the relevant case of continuous variable quantum teleportation protocols implemented using two-mode Gaussian states with a limited degree of entang...
[Phys. Rev. Lett. 119, 120503] Published Thu Sep 21, 2017

Author(s): Shuntaro Takeda and Akira Furusawa
We propose a scalable scheme for optical quantum computing using measurement-induced continuous-variable quantum gates in a loop-based architecture. Here, time-bin-encoded quantum information in a single spatial mode is deterministically processed in a nested loop by an electrically programmable gat...
[Phys. Rev. Lett. 119, 120504] Published Thu Sep 21, 2017

Author(s): Juan Bermejo-Vega, Nicolas Delfosse, Dan E. Browne, Cihan Okay, and Robert Raussendorf
A central question in quantum computation is to identify the resources that are responsible for quantum speed-up. Quantum contextuality has been recently shown to be a resource for quantum computation with magic states for odd-prime dimensional qudits and two-dimensional systems with real wave funct...
[Phys. Rev. Lett. 119, 120505] Published Thu Sep 21, 2017

Author(s): Anurag Anshu, Vamsi Krishna Devabathini, and Rahul Jain
Compression of a message up to the information it carries is key to many tasks involved in classical and quantum information theory. Schumacher [B. Schumacher, Phys. Rev. A 51, 2738 (1995)] provided one of the first quantum compression schemes and several more general schemes have been developed eve...
[Phys. Rev. Lett. 119, 120506] Published Thu Sep 21, 2017

Quantum mechanics provides means of generating genuine randomness that is
impossible with deterministic classical processes. Remarkably, the
unpredictability of randomness can be certified in a self-testing manner that
is independent of implementation devices. Here, we present an experimental
demonstration of self-testing quantum random number generation based on an
detection-loophole free Bell test with entangled photons. In the randomness
analysis, without the assumption of independent identical distribution, we

Cooling the rotation and the vibration of molecules by broadband light
sources was possible for trapped molecular ions or ultracold molecules. Because
of a low power spectral density, the cooling timescale has never fell below
than a few milliseconds. Here we report on rotational and vibrational cooling
of a supersonic beam of barium monofluoride molecules in less than 440 $\mu$s.
Vibrational cooling was optimized by enhancing the spectral power density of a

Wiesner's unforgeable quantum money scheme is widely celebrated as the first
quantum information application. Based on the no-cloning property of quantum
mechanics, this scheme allows for the creation of credit cards used in
authenticated transactions offering security guarantees impossible to achieve
by classical means. However, despite its central role in quantum cryptography,
its experimental implementation has remained elusive because of the lack of
quantum memories and of practical verification techniques. Here, we

In the model of gate-based quantum computation, the qubits are controlled by
a sequence of quantum gates. In superconducting qubit systems, these gates can
be implemented by voltage pulses. The success of implementing a particular gate
can be expressed by various metrics such as the average gate fidelity, the
diamond distance, and the unitarity. We analyze these metrics of gate pulses
for a system of two superconducting transmon qubits coupled by a resonator, a

This paper presents a Lyapunov based controller to stabilize and manipulate
an observed quantum system. The proposed control is applied to the stochastic
Schrodinger equation. In order to ensure the stability of the system at the
desired final state, the conventional Ito formula is further extended to the
un-differentiable random processes. Using this extended Ito formula, a novel
stochastic stability theorem is developed. Continued by another convergence

We study the spin-1 bilinear-biquadratic model on the complete graph of N
sites, i.e., when each spin is interacting with every other spin with the same
strength. Because of its complete permutation invariance, this Hamiltonian can
be rewritten as the linear combination of the quadratic Casimir operators of
su(3) and su(2). Using group representation theory, we explicitly diagonalize
the Hamiltonian and map out the ground-state phase diagram of the model.
Furthermore, the complete energy spectrum, with degeneracies, is obtained