Phonon Antibunching Research Articles

Unconventional phonon blockade effect in array of three coupled weakly nonlinear nanomechanical resonators

Phonon antibunching, a phenomenon arising from the quantum statistics of mechanical vibrations, has attracted significant attention due to its potential applications in quantum information processing, sensing, and energy harvesting. Here, we present a comprehensive investigation of phonon antibunching in a system consisting of three weakly nonlinear coupled nanomechanical resonators. We analytically derive and study the antibunching behavior of phonons in the proposed system and bring insight into the underlying mechanisms. The optimal phonon blockade results from destructive quantum interference due to distinct two-phonon excitation pathways. Due to this quantum interference, these unconventional phonon blockade systems can achieve antibunched statistics even in weakly nonlinear regimes, in contrast to conventional phonon blockade systems that require strong nonlinearity. We show that with the inclusion of an additional resonator, there are multiple additional two-phonon excitation pathways compared to two resonator cases, which results in stronger phonon antibunching and supports single phonon for longer duration. These findings are interesting for practical phononics using coupled-resonator systems.

Quantum synchronization in quadratically coupled quantum van der Pol oscillators

We implement nonlinear anharmonic interaction in the coupled van der Pol oscillators to investigate the quantum synchronization behavior of the systems. We study the quantum synchronization in two oscillator models, coupled quantum van der Pol oscillators and anharmonic self-oscillators. We demonstrate that the considered systems exhibit a high-order synchronization through coupling in both classical and quantum domains. We show that, due to the anharmonicity of the nonlinear interaction between the oscillators, the system exhibits phonon blockade in the phase-locking regime, which is a pure nonclassical effect and has not been observed in the classical domain. We also demonstrate that, for coupled anharmonic oscillators, the system shows a multiple resonance phase-locking behavior due to nonlinear interaction. We point out that the synchronization blockade arises due to strong anticorrelation between the oscillators, which leads to phonon antibunching in the same parametric regime. In the anharmonic oscillator case we illustrate the simultaneous occurrence of bunching and antibunching effects as a consequence of simultaneous negative and positive correlation between the anharmonic oscillators. We examine the aforementioned characteristic features in the frequency entrainment of the oscillators using a power spectrum where one can observe normal mode splitting and the Mollow triplet in the strong coupling regime. Finally, we propose a possible experimental realization for the considered system in the trapped ion and optomechanical setting.

Enhanced Phonon Antibunching in a Circuit Quantum Acoustodynamical System Containing Two Surface Acoustic Wave Resonators.

We propose a scheme to implement the phonon antibunching and phonon blockade in a circuit quantum acoustodynamical system containing two surface acoustic wave (SAW) resonators coupled to a superconducting qubit. In the cases of driving only one SAW resonator and two SAW resonators, we investigate the phonon statistics by numerically calculating the second-order correlation function. It is found that, when only one SAW cavity is resonantly driven, the phonon antibunching effect can be achieved even when the qubit–phonon coupling strength is smaller than the decay rates of acoustic cavities. This result physically originates from the quantum interference between super-Poissonian statistics and Poissonian statistics of phonons. In particular, when the two SAW resonators are simultaneously driven under the mechanical resonant condition, the phonon antibunching effect can be significantly enhanced, which ultimately allows for the generation of a phonon blockade. Moreover, the obtained phonon blockade can be optimized by regulating the intensity ratio of the two SAW driving fields. In addition, we also discuss in detail the effect of system parameters on the phonon statistics. Our work provides an alternative way for manipulating and controlling the nonclassical effects of SAW phonons. It may inspire the engineering of new SAW-based phonon devices and extend their applications in quantum information processing.

Novel hermetically sealed device to realize unconventional phonon blockade at near-micron dimensions and milliKelvin temperatures

This paper proposes a novel design for a hermetically sealable device, consisting of charged linear and nonlinear membranes driven in the gigahertz range in vacuum setting, as a source of antibunched single phonons. Constraints for effecting phonon antibunching are found using the stationary Liouville–von Neumann master equation. Using analytical calculations and material and geometry optimization, we show that sizes of the proposed system can be upscaled to the near-micrometer range in a trade-off with the system operating temperature. The results are significant to realize quantum phononics, which has much promise as a modality for sensing and computing applications.

Highly nonclassical phonon emission statistics through two-phonon loss of van der Pol oscillator

The ability to produce a nonclassical wave in a system is essential for advances in quantum communication and computation. Here, we propose a scheme to generate highly nonclassical phonon emission statistics—an antibunched wave in a quantum van der Pol (vdP) oscillator subject to external driving, both single- and two-phonon losses. It is found that phonon antibunching depends significantly on the nonlinear two-phonon loss of the vdP oscillator, where the degree of the antibunching increases monotonically with the two-phonon loss, and the distinguished parameter regimes with optimal antibunching and single-phonon emission are identified clearly. In addition, we give an in-depth insight into strong antibunching in the emitted phonon statistics by analytical calculations using a three-oscillator-level model, which agree well with the full numerical simulations employing both a master-equation approach and a Schrödinger-equation approach at weak driving. In turn, the fluorescence phonon emission spectra of the vdP oscillator, given by the power spectral density, are also evaluated. We further show that high phonon emission amplitudes, simultaneously accompanied by strong phonon antibunching, are attainable in the vdP system, which are beneficial to the correlation measurement in practical experiments. Our approach only requires a single vdP oscillator, without the need for reconfiguring the two coupled nonlinear resonators or the complex nanophononic structures as compared to the previous blockade schemes. The present scheme could inspire methods to achieve antibunching in other systems.

Phonon blockade induced by a non-Hermitian Hamiltonian in a nanomechanical resonator coupled with a qubit

Nanomechanical resonator has important applications in the field of high-precision detection because it has a high-<i>Q</i> factor, high vibration frequency, small size, and other excellent characteristics. Superconducting qubit has very large magnetic dipole moments, so it can be easily combined with nanomechanical resonator. Furthermore, the system parameters including frequency and coupling strength can be designed according to requirements beforehand, which makes a superconducting qubit an ideal artificial atom. Compared with natural atom, superconducting qubit has abundant energy levels. For these reasons, nanomechanical system has aroused wide interest in the engineering, electron, physical and other fields of science and technology. According to the recent research, a new approach to the zero eigenvalues of non-Hermitian Hamiltonian is applied to the optomechanical system. It was found that the scheme is superior to conventional photon blockade (CPB) and unconventional photon blockade (UPB) in the cavity quantum electrodynamics (QED) system. So we propose a scheme to induce phonon blockade in order to explore a new avenue to the research about phonon blockades in the quantum open system. We study the phonon blockade in an optomechanical system that a qubit is coupled with nanomechanical resonator (NAMR) driven by two external weakly driving fields respectively in this way. In this paper, the Hamiltonian of such a system can be treated by the non-Hermitian Hamiltonian and it can be described in the form of matrix. Then the phenomenon of phonon blockade occurs when all the eigenvalues in the form of matrix are equal to zero. It is found that strong phonon antibunching can be triggered in both strong and weak nonlinearity when we use the method which has been already used in a gain optical cavity system. The distinct result reflects the advantage of our approach which possesses some outstanding characters between the ordinary methods (conventional phonon blockade and unconventional phonon blockade). In addition, the effect of our avenue on phonon blockade is analyzed and also the distinction between the conventional phonon blockade (CPNB) and unconventional phonon blockade (UPNB) is compared with each other in detail. By analytical calculation, the optimal conditions are given and the underlying physical mechanism is explained. In the comparison between CPNB and UPNB, we show the superiority of our scheme through some graphs. Finally, we describe briefly the measurements of phonon blockade in the NAMR-qubit system via a superconducting cavity. The proposal may provide a theoretical way to guide the manufacture of phonon devices in the future. The results obtained here may have a great significance and application in the field of quantum information processing and precision measurement.

Tunable phonon blockade in quadratically coupled optomechanical systems

We theoretically investigate the phonon statistics of a quadratically coupled optomechanical system, in which an effective second-order nonlinear interaction between an optical mode and a mechanical mode is induced by a strong optical driving field on two-phonon red-sideband resonance. We show that strong phonon antibunching can be observed even if the strength of the effective second-order nonlinear interaction is much weaker than the decay rates of the system, by driving the optical and mechanical modes with weak driving fields respectively. Moreover, the phonon statistics can be dynamically controlled by tuning the strengths and the phase difference of the weak driving fields. The scheme proposed here can be used to realize tunable single-phonon sources with quadratically optomechanical coupling.

Phonon antibunching effect in coupled nonlinear micro/nanomechanical resonator at finite temperature

In this study, we investigate the phonon antibunching effect in a coupled nonlinear micro/nanoelectromechanical system (MEMS/NEMS) resonator at a finite temperature. In the weak driving limit, the optimal condition for phonon antibunching is given by solving the stationary Liouville-von Neumann master equation. We show that at low temperature, the phonon antibunching effect occurs in the regime of weak nonlinearity and mechanical coupling, which is confirmed by analytical and numerical solutions. We also find that thermal noise can degrade or even destroy the antibunching effect for different mechanical coupling strengths. Furthermore, a transition from strong antibunching to bunching for phonon correlation has been observed in the temperature domain. Finally, we find that a suitably strong driving in the finite-temperature case would help to preserve an optimal phonon correlation against thermal noise.

Sub-Poissonian phonon lasing in three-mode optomechanics

We propose to use the resonant enhancement of the parametric instability in an optomechanical system of two optical modes coupled to a mechanical oscillator to prepare mechanical states with sub-Poissonian phonon statistics. Strong single photon coupling is not required. The requirements regarding sideband resolution, circulating cavity power and environmental temperature are in reach with state of the art parameters of optomechanical crystals. Phonon antibunching can be verfied in a Hanburry-Brown-Twiss measurement on the output field of the optomechanical cavity.

Lasing and antibunching of optical phonons in semiconductor double quantum dots

We theoretically propose optical phonon lasing in a double quantum dot (DQD) fabricated on a semiconductor substrate. No additional cavity or resonator is required. An electron in the DQD is found to be coupled to only two longitudinal optical phonon modes that act as a natural cavity. When the energy level spacing in the DQD is tuned to the phonon energy, the electron transfer is accompanied by the emission of the phonon modes. The resulting non-equilibrium motion of electrons and phonons is analyzed by the rate equation approach based on the Born–Markov–Secular approximation. We show that lasing occurs for pumping the DQD via electron tunneling at a rate much larger than the phonon decay rate, whereas phonon antibunching is observed in the opposite regime of slow tunneling. Both effects disappear by an effective thermalization induced by the Franck–Condon effect in a DQD fabricated in a suspended carbon nanotube with strong electron–phonon coupling.

Cooling in the single-photon strong-coupling regime of cavity optomechanics

In this Rapid Communication we discuss how red-sideband cooling is modified in the single-photon strong-coupling regime of cavity optomechanics where the radiation pressure of a single photon displaces the mechanical oscillator by more than its zero-point uncertainty. Using Fermi's golden rule we calculate the transition rates induced by the optical drive without linearizing the optomechanical interaction. In the resolved-sideband limit we find multiple-phonon cooling resonances for strong single-photon coupling that lead to nonthermal steady states including the possibility of phonon antibunching. Our study generalizes the standard linear cooling theory.