TY - JOUR
T1 - Giant nonlinearity via breaking parity-time symmetry
T2 - A route to low-threshold phonon diodes
AU - Zhang, Jing
AU - Peng, Bo
AU - Özdemir, Şahin Kaya
AU - Liu, Yu Xi
AU - Jing, Hui
AU - Lü, Xin You
AU - Liu, Yu Long
AU - Yang, Lan
AU - Nori, Franco
N1 - Publisher Copyright:
© 2015 American Physical Society.
PY - 2015/9/8
Y1 - 2015/9/8
N2 - Nonreciprocal devices that permit wave transmission in only one direction are indispensible in many fields of science including, e.g., electronics, optics, acoustics, and thermodynamics. Manipulating phonons using such nonreciprocal devices may have a range of applications such as phonon diodes, transistors, switches, etc. One way of achieving nonreciprocal phononic devices is to use materials with strong nonlinear response to phonons. However, it is not easy to obtain the required strong mechanical nonlinearity, especially for few-phonon situations. Here we present a general mechanism to amplify nonlinearity using parity-time (PT)-symmetric structures, and show that an on-chip microscale phonon diode can be fabricated using a PT-symmetric mechanical system, in which a lossy mechanical resonator with very weak mechanical nonlinearity is coupled to a mechanical resonator with mechanical gain but no mechanical nonlinearity. When this coupled system transits from the PT-symmetric regime to the broken-PT-symmetric regime, the mechanical nonlinearity is transferred from the lossy resonator to the one with gain, and the effective nonlinearity of the system is significantly enhanced. This enhanced mechanical nonlinearity is almost lossless because of the gain-loss balance induced by the PT-symmetric structure. Such an enhanced lossless mechanical nonlinearity is then used to control the direction of phonon propagation, and can greatly decrease (by over three orders of magnitude) the threshold of the input-field intensity necessary to observe the unidirectional phonon transport. We propose an experimentally realizable lossless low-threshold phonon diode of this type. Our study opens up perspectives for constructing on-chip few-phonon devices and hybrid phonon-photon components.
AB - Nonreciprocal devices that permit wave transmission in only one direction are indispensible in many fields of science including, e.g., electronics, optics, acoustics, and thermodynamics. Manipulating phonons using such nonreciprocal devices may have a range of applications such as phonon diodes, transistors, switches, etc. One way of achieving nonreciprocal phononic devices is to use materials with strong nonlinear response to phonons. However, it is not easy to obtain the required strong mechanical nonlinearity, especially for few-phonon situations. Here we present a general mechanism to amplify nonlinearity using parity-time (PT)-symmetric structures, and show that an on-chip microscale phonon diode can be fabricated using a PT-symmetric mechanical system, in which a lossy mechanical resonator with very weak mechanical nonlinearity is coupled to a mechanical resonator with mechanical gain but no mechanical nonlinearity. When this coupled system transits from the PT-symmetric regime to the broken-PT-symmetric regime, the mechanical nonlinearity is transferred from the lossy resonator to the one with gain, and the effective nonlinearity of the system is significantly enhanced. This enhanced mechanical nonlinearity is almost lossless because of the gain-loss balance induced by the PT-symmetric structure. Such an enhanced lossless mechanical nonlinearity is then used to control the direction of phonon propagation, and can greatly decrease (by over three orders of magnitude) the threshold of the input-field intensity necessary to observe the unidirectional phonon transport. We propose an experimentally realizable lossless low-threshold phonon diode of this type. Our study opens up perspectives for constructing on-chip few-phonon devices and hybrid phonon-photon components.
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U2 - 10.1103/PhysRevB.92.115407
DO - 10.1103/PhysRevB.92.115407
M3 - Article
AN - SCOPUS:84942465922
SN - 1098-0121
VL - 92
JO - Physical Review B-Condensed Matter
JF - Physical Review B-Condensed Matter
IS - 11
M1 - 115407
ER -