Observation of Ultrastrong Magnon-Magnon Coupling in YFeO3 Using Terahertz Magnetospectroscopy

Makihara, Takuma; Noe, G. Timothy; Li, Xinwei; Hayashida, Kenji; Peraca, Nicolás Márquez; Tian, K.; Ma, Xiaoxuan; Jin, Zuanming; Ren, Wei; Ma, Guohong; Cao, Shixun; Katayama, Ikufumi; Takeda, Jun; Turchinovich, Dmitry; Nojiri, Hiroyuki; Bamba, Motoaki; Kono, Junichiro

doi:10.1364/cleo_qels.2020.fm4d.4

Cited by 3 publications

(5 citation statements)

References 8 publications

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“…In particular, it is known that the thermal and quantum fluctuations of photons and atoms show characteristic behaviors around the SRPT [59]. It is also known that the ground state of an ultrastrongly coupled system is a quantum squeezed vacuum even in the normal phase [3,[60][61][62][63][64], and strong two-mode squeezing at the SRPT has been demonstrated numerically [65]. Our on-going terahertz magnetospectroscopy experiments of Er x Y 1−x FeO 3 around the LTPT [66] will experimentally examine such characteristic quantum squeezing at the thermal and quantum SRPTs.…”

Section: Discussionmentioning

confidence: 99%

Magnonic Superradiant Phase Transition

Bamba,

Li,

Peraca

et al. 2020

Preprint

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We show that the low-temperature phase transition in ErFeO3 that occurs at a critical temperature of ∼ 4 K can be described as a magnonic version of the superradiant phase transition (SRPT). The role of photons in the quantum-optical SRPT is played by Fe 3+ magnons, while that of two-level atoms is played by Er 3+ spins. Our spin model, which is reduced to an extended Dicke model, takes into account the short-range, direct exchange interactions between Er 3+ spins in addition to the longrange Er 3+ -Er 3+ interactions mediated by Fe 3+ magnons. By using realistic parameters determined by recent terahertz magnetospectroscopy and magnetization experiments, we demonstrate that it is the cooperative, ultrastrong coupling between Er 3+ spins and Fe 3+ magnons that causes the phase transition. This work thus proves ErFeO3 to be a unique system that exhibits a SRPT in thermal equilibrium, in contrast to previous observations of laser-driven non-equilibrium SRPTs. III. LOW-TEMPERATURE PHASE TRANSITION IN ErFeO3

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Section: Discussionmentioning

confidence: 99%

Magnonic Superradiant Phase Transition

Bamba,

Li,

Peraca

et al. 2020

Preprint

Self Cite

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“…However, it could be implemented in condensed matter systems using matter-matter interactions; for instance, Dicke cooperativity was experimentally realized in [31] with spin-magnon interactions in the USC regime. Moreover, recent terahertz magnetospectroscopy experiments [7,28,67] suggest that the magnonic version of the SPT is within reach [68].…”

Section: Discussionmentioning

confidence: 99%

“…Recall that when light interacts with natural atoms, g 1 must be equal to g 2 . However, recent experiments on matter-matter interactions (specifically magnon-magnon interaction) show that one can have surprising situations where g 2 > g 1 [7,28]. There is also evidence that such anisotropy (g 1 = g 2 ) can better describe the experimental data of the USC between electromagnetic radiation with artificial atoms made of superconducting quantum circuits [29].…”

Section: The Hopfield Modelmentioning

confidence: 99%

Spectroscopy and critical quantum thermometry in the ultrastrong coupling regime

Salado-Mejía

Román-Ancheyta

Soto‐Eguibar

et al. 2021

Quantum Sci. Technol.

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We present an exact analytical solution of the anisotropic Hopfield model, and we use it to investigate in detail the spectral and thermometric response of two ultrastrongly coupled quantum systems. Interestingly, we show that depending on the initial state of the coupled system, the vacuum Rabi splitting manifests significant asymmetries that may be considered spectral signatures of the counterintuitive decoupling effect. Using the coupled system as a thermometer for quantum thermodynamics applications, we obtain the ultimate bounds on the estimation of temperature that remain valid in the ultrastrong coupling regime. Remarkably, if the system performs a quantum phase transition, the quantum Fisher information exhibits periodic divergences, suggesting that one can have several points of arbitrarily high thermometric precision for such a critical quantum sensor.

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“…For instance, Dicke cooperativity was experimentally realized in [29] with spin-magnon interactions in the USC regime. Moreover, recent terahertz magnetospectroscopy experiments [6,26,52] suggest that the magnonic version of the SPT is within reach [53].…”

Section: Discussionmentioning

confidence: 99%

“…Recall that, when light interacts with natural atoms, g 1 must be equal to g 2 . However, recent experiments on matter-matter interactions (specifically magnon-magnon interaction) show that one can have astonishing situations when g 2 > g 1 [6,26]. There is also evidence that such anisotropy (g 1 = g 2 ) can better describe the experimental data of the USC between electromagnetic radiation with artificial atoms made of superconducting quantum circuits [27].…”

Section: The Hopfield Modelmentioning

confidence: 99%

Spectroscopy and critical quantum thermometry in the ultrastrong coupling regime

Salado-Mejía,

Román-Ancheyta,

Soto-Eguibar

et al. 2020

Preprint

View full text Add to dashboard Cite

We present an exact analytical solution of the anisotropic Hopfield model, and we use it to investigate in detail the spectral and thermometric response of two ultrastrongly coupled quantum systems. Interestingly, we show that depending on the initial state of the coupled system, the vacuum Rabi splitting manifests significant asymmetries that may be considered spectral signatures of the counterintuitive decoupling effect.Using the coupled system as a thermometer for quantum thermodynamics applications, we obtain the ultimate bounds on the estimation of temperature that remain valid in the ultrastrong coupling regime. Remarkably, if the system performs a quantum phase transition, the quantum Fisher information exhibits periodic divergences, suggesting that one can have several points of arbitrarily high thermometry precision for such a critical quantum sensor.

show abstract

Observation of Ultrastrong Magnon-Magnon Coupling in YFeO3 Using Terahertz Magnetospectroscopy

Abstract: We studied magnon-magnon ultrastrong coupling in YFeO3 using terahertz magnetospectroscopy in magnetic fields up to 30 T, which led to an extreme breakdown of the rotating-wave approximation where the counter-rotating term dominates the co-rotating term.

Cited by 3 publications

References 8 publications

Magnonic Superradiant Phase Transition

Magnonic Superradiant Phase Transition

Spectroscopy and critical quantum thermometry in the ultrastrong coupling regime

Spectroscopy and critical quantum thermometry in the ultrastrong coupling regime

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