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Quantum hypothesis testing—the task of distinguishing quantum states—enjoys surprisingly deep connections with the theory of entanglement. Recent findings have reopened the biggest questions in hypothesis testing and reversible entanglement manipulation.

The sensitive measurement of physical quantities offers a wide range of applications in fundamental and applied science. Cai et al. propose a hybrid technology combining colour centres in diamond and piezoactive layers to realize force, pressure and electric field sensors with nanoscale resolution.

It is already known that the theory of quantum entanglement shares some analogies with the laws of thermodynamics. Now a rigorous and general link between the two fields has been established.

Photosynthesis is remarkably efficient. The transport of optically generated excitons from absorbing pigments, through protein complexes, to reaction centres is nearly perfect. Simulations now uncover the microscopic mechanism that drives this coherent behaviour: interactions between the excitons and the vibrational modes of the pigment-protein complex.

Single electrons of solid-state defects can be used to detect nearby nuclear spins, but so far only a few at a time have been resolved. Here the authors propose an approach based on delayed entanglement echo that demonstrates improved detection and manipulation capabilities of nuclear spins by an NV centre.

Controllable quantum systems can be used to emulate intractable quantum many-body problems, but such simulators remain an experimental challenge. Nuclear spins on a diamond surface promise an improved large-scale quantum simulator operating at room temperature.

Multimode vibronic mixing in model photosynthetic systems revealed by numerically exact simulations is shown to strongly modify linear and non-linear optical responses and facilitate the persistence of coherent dynamics.

The use of multi-particle systems in quantum-gravity phenomenology should take into account the expected suppression with increasing number of constituent particles N. Here, the authors analyse the case of polynomial scaling with N, and give bounds from previous experiments with macroscopic pendula.

By developing full quantum detector tomography, researchers simultaneously characterize the wave- and photon-number sensitivities of quantum-optical detectors to yield the largest ever parametrization in a quantum tomography experiment. The presented results reveal the role of coherence in quantum measurements and demonstrate the tunability of hybrid quantum-optical detectors.

Detection of coherent energy transport has fuelled claims that quantum effects make photosynthesis more efficient. Experiments now show that the interplay between electronic and vibrational motion also sustains coherence in the subsequent charge-separation process.

Quantum collision models are pivotal for simulating open quantum systems, yet lack comprehensive error certification. The authors analytically derive Markovian and non-Markovian collision models from chain mapping techniques, identifying a critical error source, thus elevating collision models to numerically exact methods and enhancing their reliability across quantum simulations.

Understanding of charge transfer dynamics is essential to the design of high-performance organic semiconductors for optoelectronic applications. Here, the authors show that excitons, polaron pairs and a long-lived vibrational mode are strongly coupled to each other up to 1 picosecond in polythiophene.

Two-dimensional spectroscopy revealed oscillatory signals in photosynthesis’ exciton dynamics, but crowded spectra impede the identification of what sustains the oscillations. Here the authors probe an J-aggregate, whose uncongested response shows that vibronic coupling is responsible for the sustained coherence.

Direct quantum state tomography—deducing the state of a system from measurements—is mostly unfeasible due to the exponential scaling of measurement number with system size. The authors present two new schemes, which scale linearly in this respect, and can be applied to a wide range of quantum states.

The dynamics of charge separation, where the underlying mechanisms are a complex interplay of many contributing factors, govern the properties and performance of solar cells. Here, the authors investigate the role of vibrational motion in the charge dynamics of donor-acceptor networks using a non-perturbative simulation tool.

Traditionally quantum state tomography is used to characterize a quantum state, but it becomes exponentially hard with the system size. An alternative technique, matrix product state tomography, is shown to work well in practical situations.