Phys.org May 14, 2024 Periodic temporal modulation of Hamiltonians can induce geometrical and topological phenomena in the dynamics of quantum states. Using the interference between two lasers an international team of researchers (Japan, USA – industry, Singapore, Australia, Germany) demonstrated an off-resonant optical lattice for a polariton condensate with controllable potential depths and nearest-neighbour coupling strength. Temporal modulation was introduced via a gigahertz frequency detuning between pump lasers, creating a polariton ‘conveyor belt’. The breaking of time-reversal symmetry caused band structures to become non-reciprocal and acquired a universal tilt. The non-reciprocal tilting was connected to the non-trivial topology of the […]
Tag Archives: Quasiparticles
Cosmic rays may soon stymie quantum computing
MIT News August 26, 2020 Superconducting qubits are used for high-fidelity operations. However, the density of the broken Cooper pairs, referred to as quasiparticles, is orders of magnitude higher than the value predicted at equilibrium suggesting that another generation mechanism exists. A team of researchers in the US (MIT, Pacific Northwest National Laboratory, MIT Lincoln Laboratory) has provided evidence that ionizing radiation from environmental radioactive materials and cosmic rays contributes to this observed difference. The effect of ionizing radiation leads to an elevated quasiparticle density, which they predict would ultimately limit the coherence times of superconducting qubits. They demonstrated that […]
Being exceptional in higher dimensions
Nanowerk July 1, 2020 By connecting electromagnetic waves and magnetism to create a system made of magnon polaritons an international team of researchers (USA- Argonne National Laboratory, UK) has demonstrated the existence of an “exceptional surface”. Through experiments, they have shown that EPs form a three-dimensional exceptional surface (ES) when the system is tuned in a four-dimensional synthetic space. They found that an exceptional saddle point (ESP) exists in the ES which originates from the unique couplings between magnons and microwave photons. It exhibits unique anisotropic behaviors in both the real and imaginary parts of the eigenfrequencies. The findings open […]