51社区黑料

Harnessing higher-dimensional fluctuations in an information engine

We show how an information engine can convert horizontal thermal 鈥渏iggles鈥� (fluctuations) into the lifting of a weight against gravity. Remarkably, horizontal fluctuations turn out to be more valuable than vertical ones. This design modularizes the roles of fluctuation harvesting and energy storage, suggesting a route toward more practical devices

Angle-dependent magnetoresistance including magnetic breakdown

Angle-dependent magnetoresistance (ADMR) is a powerful tool for probing Fermi surfaces of layered metals, providing valuable insights into the physics of quantum materials such as cuprate and organic superconductors. In ADMR experiments, the interlayer electrical resistivity is measured as the orientation of the applied magnetic field changes relative to two-dimensional conducting layers. A related phenomenon, magnetic breakdown, occurs when electrons tunnel between adjacent segments of the Fermi surface at strong magnetic fields. We study the effect of magnetic breakdown on ADMR for realistic Fermi surfaces, which are anisotropic in momentum space and incorporate thermal effects.

An Optically Resolved Hyperfine Interaction at Telecom Wavelengths within the Excited State of Interstitial Aluminum in Silicon

Nuclear-spin qubits in the solid state have demonstrated exceptional coherence times, making them exceptional candidates for quantum hardware. Integrating them into quantum networks requires introducing an efficient optical interface for distributed entanglement, such as the spin-dependent optical transitions of an electron in a silicon colour centre. While typical interfaces rely on paramagnetic ground states, recent studies have explored centres with diamagnetic ground states. In such systems, since hyperfine coupling is exclusively enabled within the excited state, a nuclear spin protection scheme is enabled after the system returns to the ground state. The electron, therefore, operates as an ancillary qubit for nuclear spin initialization and readout for future quantum repeater node.

Coherent optical properties of the silicon T centre

Silicon colour centres have emerged as promising spin-photon interfaces (SPIs) to provide a platform for networked quantum computing and long-distance quantum communications. The T centre is at the forefront of silicon colour centre SPIs with spin-dependent optical emission in the telecommunications O-band. Usage of T centres for quantum computing and communications will require control of both the optical and spin qubits. Though T centre spin control has been demonstrated with RF and MW fields, an all-optical approach would alleviate many technical requirements, substantially lower operational heat loads, and allow fundamentally faster gates. Here, we report progress towards T centre optical control using telecommunications band lasers. We demonstrate optical Rabi oscillations and achieve a significant improvement in optical coherence by reducing spectral diffusion with a resonance checking scheme. We next demonstrate optical coherent population trapping (CPT) in the T centre鈥檚 electron spin. This is the first coherent optical spin preparation on the T centre. Using CPT we perform high resolution optical spectroscopy of the T centre ground state. These results demonstrate the first steps towards optically driven spin control of the silicon T centre.