Observation of an anti-PT-symmetric exceptional point and energy-difference conserving dynamics in electrical circuit resonators

Abstract

Parity-time (PT) symmetry and associated non-Hermitian properties in open physical systems have been intensively studied in search of new interaction schemes and their applications. Here, we experimentally demonstrate an electrical circuit producing key non-Hermitian properties and unusual wave dynamics grounded on anti-PT (APT) symmetry. Using a resistively coupled amplifying-LRC-resonator circuit, we realize a generic APT-symmetric system that enables comprehensive spectral and time-domain analyses on essential consequences of the APT symmetry. We observe an APT-symmetric exceptional point (EP), inverse PT-symmetry breaking transition, and counterintuitive energy-difference conserving dynamics in stark contrast to the standard Hermitian dynamics keeping the system’s total energy constant. Therefore, we experimentally confirm unique properties of APT-symmetric systems, and further development in other areas of physics may provide new wave-manipulation techniques and innovative device-operation principles.

Observation of parity-time symmetry breaking in a single-spin system

“…The Hermiticity requirement may be replaced by PT symmetry to develop an alternative formulation of quantum mechanics [2, 3]. A series of experiments have been carried out with classical systems including optics [4], electronics [5][6][7], microwaves[8], mechanics [9] and acoustics [10][11][12]. However, there are few experiments to investigate PT symmetric physics in quantum systems.…”

PT-Symmetry in Hartree–Fock Theory

“…some of the eigenfunctions ofĤ are not simultaneously eigenfunctions of P T ), while the region where the entire spectrum is real is referred to as the unbroken P T -symmetry region. Amazingly, these P T -symmetry phase transitions have been observed experimentally in electronics, microwaves, mechanics, acoustics, atomic systems and optics, 42,43,[46][47][48][49][50][51][52][53][54][55][56][57][58][59][60][61] and the parameter values where symmetry breaking occurs [ = 0 in the case of Hamiltonian (3)] correspond to the appearance of exceptional points, 52,60,[62][63][64][65][66][67][68][69][70] the non-Hermitian analogues of conical intersections. 71 B. Fermions P T -symmetric systems involving fermions are much less studied than their bosonic counterparts.…”

Higher-order exceptional points in ferromagnetic trilayers

“…Hamiltonian obeying the parity-time (PT ) symmetry constitutes a special non-Hermitian system, which is invariant under combined parity P and time-reversal T operations. It has attracted a lot of attention due to both the fundamental interest in quantum theory [17][18][19] and the promising application in many fields [20][21][22], such as optics [23][24][25], tight-binding modeling [26,27], acoustics [28,29], electronics [30,31], and very recently in spintronics [12][13][14][15][16]. A PT -symmetric Hamiltonian could exhibit entirely real spectra and a spontaneous symmetry breaking accompanied by a real-to-complex spectra phase transition at the exceptional point (EP) where two or more eigenvalues and their corresponding eigenvectors coalesce simultaneously.…”