Quantum Echo
Meme
"Quantum Echo" can refer to different concepts depending on the context:
Scientific Phenomenon: In quantum physics, a quantum echo occurs when quantum states, such as spins in a material, realign after being disturbed, similar to how sound echoes. This effect has applications in quantum computing and spintronics. https://techbriefly.com/2020/10/22/quantum-echo-opens-possibilities-for-new-technologies/
Recent Experiment: A controversial claim suggests that a quantum experiment at Google's lab may have caused a measurable disturbance in Earth's magnetic field, leading to what some call a "Quantum Echo." This phenomenon allegedly propagated across the magnetosphere, raising questions about quantum interactions on a planetary scale. https://www.youtube.com/watch?v=w7_geoGq8pE
Context
Nonlinearities in quantum systems are fundamentally characterized by the interplay of phase coherences, their interference, and state transition amplitudes. Yet the question of how quantum coherence and interference manifest in transient, massive Higgs excitations, prevalent within both the quantum vacuum and superconductors, remains elusive. One hallmark example is photon echo, enabled by the generation, preservation, and retrieval of phase coherences amid multiple excitations. Here we reveal an unconventional Quantum Echo arising from the Higgs coherence in superconductors, and identify distinctive signatures attributed to Higgs anharmonicity. A terahertz pulse-pair modulation of the superconducting gap generates a “time grating” of coherent Higgs population, which scatters echo signals distinct from conventional spinand photon-echoes in atoms and semiconductors. These manifestations appear as Higgs echo spectral peaks occurring at frequencies forbidden by equilibrium particle-hole symmetry, an “asymmetric” delay in the echo formation from the dynamics of the “reactive” superconducting state, and negative time signals arising from Higgs-quasiparticle anharmonic coupling. The Higgs interference and anharmonicity control the decoherence of driven superconductivity and may enable applications in quantum memory and entanglement.
https://arxiv.org/pdf/2312.10912
