Spontaneous Plasticity of Multineuronal Activity Patterns in Activated Hippocampal Networks

Using functional multineuron imaging with single-cell resolution, we examined how hippocampal networks by themselves change the spatiotemporal patterns of spontaneous activity during the course of emitting spontaneous activity. When extracellular ionic concentrations were changed to those that mimicked in vivo conditions, spontaneous activity was increased in active cell number and activity frequency. When ionic compositions were restored to the control conditions, the activity level returned to baseline, but the weighted spatial dispersion of active cells, as assessed by entropy-based metrics, did not. Thus, the networks can modify themselves by altering the internal structure of their correlated activity, even though they as a whole maintained the same level of activity in space and time

Quantum magnonics: magnon meets superconducting qubit

The techniques of microwave quantum optics are applied to collective spin excitations in a macroscopic sphere of ferromagnetic insulator. We demonstrate, in the single-magnon limit, strong coupling between a magnetostatic mode in the sphere and a microwave cavity mode. Moreover, we introduce a superconducting qubit in the cavity and couple the qubit with the magnon excitation via the virtual photon excitation. We observe the magnon-vacuum-induced Rabi splitting. The hybrid quantum system enables generation and characterization of non-classical quantum states of magnons.Comment: 10 pages, 6 figure

Heating-free, room-temperature operation of a radiofrequency-to-light signal transducer with a membrane oscillator and a built-in metasurface mirror

We present an electro-mechano-optical radiofrequency (rf)-to-light signal transducer robust against laser heating and thus operational at room temperature. A metal-free, low-loss metasurface mirror and an aluminum electrode made separately on a Si₃N₄ membrane oscillator comprise a chain of electro-mechanical and opto-mechanical systems, mediating electrical and optical signals through the (2, 2)-mode characteristic oscillation. We demonstrate up-conversion of rf signals at 175.2 MHz by 6 orders of magnitude in frequency to an optical regime with the transfer efficiency of 2.3 × 10⁻⁹, also showing stable operation due to reduced laser heating of the mirror