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The long-standing problem of determining the classical communication capacities of Gaussian bosonic channels is addressed by determining upper and lower bounds for the classical capacities of important active and passive bosonic channels. The results apply to any bosonic thermal-noise channel, including electromagnetic signaling at any frequency.

Finding a classical description of a quantum state can require resource-intensive tomography protocols. It has now been shown that, for bosonic systems, tomography is extremely inefficient in general, but can be done efficiently for some useful states.

It is an old adage in quantum physics that the observation of a system changes its properties, as exemplified by the quantum Zeno effect. Now, Burgarth et al.show that such repeated measurement of a quantum system actually enriches its dynamics, letting it explore a much larger algebra than it did before.

Transforming a quantum system with high fidelity is usually a trade-off between an increase in speed—thereby minimizing decoherence—and robustness against fluctuating control parameters. Protocols at these two extreme limits are now demonstrated and compared using Bose–Einstein condensates in optical traps.

Elegant but extremely delicate quantum procedures can increase the precision of measurements. Characterizing how they cope with the detrimental effects of noise is essential for deployment to the real world.

Lower bounds on the energy-constrained and unconstrained two-way quantum and secret-key capacities of all phase-insensitive bosonic Gaussian channels are provided. It proves that a non-zero capacity exists for all parameters where the phase-insensitive bosonic Gaussian channels are not entanglement breaking.

A proposed device—an optical analogue of the superconducting Josephson interferometer—might enable detailed studies of the role that dissipation has in strongly correlated quantum-optical systems.

Bounding the capacity of thermal attenuators would give a powerful instrument to describe decoherence occurring in optical fibres and free space links. Here, the authors improve on the existing upper bounds in the region of small thermal noise, which is of interest for quantum communication.

High-mobility graphene can play host to exciton polaritons—hybrid matter–light particles, which can form into a state known as a quantum Hall polariton fluid. Here, the authors show that electron–electron interactions can act to destabilize this state and lead to the formation of a modulated phase.

In thermodynamics, thermal properties of systems are obtained from averaging procedures which smooth out local details. Here, the authors introduce the concept of local quantum thermal susceptibility, a measure for the best achievable accuracy of estimation of temperature via local measurements.

Researchers observe Anderson localization for pairs of polarization-entangled photons in a discrete quantum walk affected by position-dependent disorder. By exploiting polarization entanglement of photons to simulate different quantum statistics, they experimentally investigate the interplay between the Anderson localization mechanism and the bosonic/fermionic symmetry of the wave function.

Estimating the capacity of quantum channels is relevant to understand at which rate quantum information can be exchanged. Here, the authors introduce multi-level amplitude damping channels that generalize the qubit amplitude damping noise model, analyse their quantum and private capacities, and exactly derive the capacities of quantum channels that are not anti-degradable.