Ultrastrong magnon–magnon coupling dominated by antiresonant interactions

Abstract

Exotic quantum vacuum phenomena are predicted in cavity quantum electrodynamics systems with ultrastrong light-matter interactions. Their ground states are predicted to be vacuum squeezed states with suppressed quantum fluctuations owing to antiresonant terms in the Hamiltonian. However, such predictions have not been realized because antiresonant interactions are typically negligible compared to resonant interactions in light-matter systems. Here we report an unusual, ultrastrongly coupled matter-matter system of magnons that is analytically described by a unique Hamiltonian in which the relative importance of resonant and antiresonant interactions can be easily tuned and the latter can be made vastly dominant. We found a regime where vacuum Bloch-Siegert shifts, the hallmark of antiresonant interactions, greatly exceed analogous frequency shifts from resonant interactions. Further, we theoretically explored the system’s ground state and calculated up to 5.9 dB of quantum fluctuation suppression. These observations demonstrate that magnonic systems provide an ideal platform for exploring exotic quantum vacuum phenomena predicted in ultrastrongly coupled light-matter systems.

Distant emitters in ultrastrong waveguide QED: Ground-state properties and non-Markovian dynamics

“…In this work, we fix our attention on natural or artificial two-level emitters, for which the SBM provides an excellent description in the USC regime, our main interest here. This ultrastrong coupling regime of light and matter has been recently achieved in several experimental systems involving superconducting circuits [53,54], semiconductors [55], organic aggregates [56], optomechanical systems [57], and others [11,58].…”

Distant emitters in ultrastrong waveguide QED: Ground-state properties and non-Markovian dynamics

“…In this work, we fix our attention on natural or artificial two-level emitters, for which the SBM provides an excellent description in the USC regime, our main interest here. This ultrastrong coupling regime of light and matter has been recently achieved in several experimental systems involving superconducting circuits [44], semiconductors [45], organic aggregates [46], optomechanical systems [47], and more [11,48].…”

Parallel generation and coding of a terahertz pulse train

“…To date, echelon mirrors have mainly been used for single-shot time-domain THz spectroscopy [39,40] and for the development of intense THz sources using the tilted-pulse front-pumping (TPFP) scheme [8,41]. The idea behind using an echelon mirror is to temporally shape the re ected optical pulse at different delay times without dispersion, i.e., while preserving the ultrashort property for each re ected optical beamlet.…”

“…The idea behind using an echelon mirror is to temporally shape the re ected optical pulse at different delay times without dispersion, i.e., while preserving the ultrashort property for each re ected optical beamlet. For single-shot THz spectroscopy, the idea is to instantaneously probe each part of a THz pulse with a segmented ultrashort probing beamlet [39,40]. In the case of intense THz generation using the TPFP con guration, a tilted pulse must be generated at the image plane in order to meet the phase matching condition inside a lithium niobate crystal along the Cherenkov angle [8,41].…”

“…Interestingly, the DMD can also act as an active echelon mirror for ultrafast pulse measurements [42] and the TPFP scheme [43]. However, in contrast to previous works [8, [39][40][41][42][43], we are interested in converting each ultrafast optical beam into a single THz pulse train at a speci c carrier frequency, thus generating a xed frequency pulse train.…”