Top PDF Quantum Squeezing of Motion in a Mechanical Resonator

Quantum Squeezing of Motion in a Mechanical Resonator

Quantum Squeezing of Motion in a Mechanical Resonator

To measure fluctuations on the zero-point level with our amplifier that adds more than 20 quanta of noise, we must average over many hours, or even days, to obtain acceptable levels of signal-to-noise. Even on these time scales, our system is very stable. We observe changes of less than 1% in the through power of our pump or probe tones, as shown in Fig. 4.12. The drift in through power we do see is most likely due to the frequency drift of our room-temperature filter cavities, as we know that their frequency is strongly temperature-dependent. Note that our measurement scheme should not be affected by system-wide changes in gain, as we always normalize the mechanical spectrum by the probe through power. Changing input gain can change the squeezing pump intra-cavity occupation, however, which could change the amount of squeezing in the mechanics. Frequency- dependent changes in input gain, like those from shifting filter cavities, can also change the probe power ratio, which can introduce errors into the measured spectra. We thus reset the filter cavities and adjust pump powers twice a day to prevent large-scale drifts.
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Quantum squeezing effects of strained multilayer graphene NEMS

Quantum squeezing effects of strained multilayer graphene NEMS

The Heisenberg uncertainty principle, or the standard quantum limit [1,2], imposes an intrinsic limitation on the ultimate sensitivity of quantum measurement sys- tems, such as atomic forces [3], infinitesimal displace- ment [4], and gravitational-wave [5] detections. When detecting very weak physical quantities, the mechanical motion of a nano-resonator or nanoelectromechanical system (NEMS) is comparable to the intrinsic fluctua- tions of the systems, including thermal and quantum fluctuations. Thermal fluctuation can be reduced by decreasing the temperature to a few mK, while quantum fluctuation, the quantum limit determined by Heisen- berg relation, is not directly dependent on the tempera- ture. Quantum squeezing is an efficient way to decrease the system quantum [6-8]. Thermomechanical noise squeezing has been studied by Rugar and Grutter [9], where the resonator motion in the fundamental mode was parametrically squeezed in one quadrature by peri- odically modulating the effective spring constant at twice its resonance frequency. Subsequently, Suh et al. [10] have successfully achieved parametric amplification and back-action noise squeezing using a qubit-coupled nanoresonator.
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Cooling a Mechanical Resonator with an Artificial Cold Resistor

Cooling a Mechanical Resonator with an Artificial Cold Resistor

Moreover, there is an overlooked technique: the resistive cooling ex- plored in the early experiments for gravitational wave detection 40 years ago [10]. A simple cold resistor was used to dissipate the thermal energy of a ton-scale mechanical resonator, and the resistor could also be artificially cold [11]. Unfortunately, they have been rarely studied ever since. We are attracted by the simplicity of this approach, and in this thesis, we study the resistive cooling with an artificial cold resistor (ACR), looking for possibil- ities to cool a miniature mechanical resonator. Although it would not be a candidate for ground state cooling, it might be an important tool resolv- ing experimental challenges. Particularly, opening an electrical access to control the motion of an “massive” (compared to those reached quantum ground state) optomechanical resonator, would be very interesting for the yet-challenging ground-state cooling experiments. A practical example is discussed in Chapter 4.
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Quasiprobability density diffusion equations for the quantum Brownian motion in a potential

Quasiprobability density diffusion equations for the quantum Brownian motion in a potential

Quantum TST as formulated for particles with separable and additive Hamiltonians in the manner just described has also been applied [20] in the context of magnetization reversal to the escape rate of the large spin model of single domain ferromagnetic particles. This model describes a ferromagnetic particle with uniaxial anisotropy with external fields applied parallel and perpendicular to the anisotropy axis. Tunnelling in such a model will be caused by the transverse field [20]. Now, the Hamiltonian of the model (which is not separable and additive as the canonical variables are now the polar angles θ and ϕ specifying the orientation of the magnetization vector) may be mapped [20] onto that of a mechanical particle moving in a double well potential. Hence the quantum TST rate described above which is a close approximation to the exact escape rate in the intermediate damping region may also be used to study thermally assisted tunnelling of the magnetization of a single domain ferromagnetic particle. The complete solution of the foregoing problem, however, essentially involves the extension of Wigner’s formalism to the phase-space description of spin systems as initiated by Stratonovich [21] and recently extended and reviewed by Klimov [22] who gave exact evolution equations for SU(2) dynamical group quasidistribution functions. Applications of the formalism include quantum decoherence in the rotation of small molecules [23], spin squeezing and spin entanglement in the semiclassical limit [24]. In the context of TST for spins described by the SU(2) rotation dynamical group we should remark that the results of the calculation of the Wigner distribution given in Section IV.IV, Eqns. (4.59) et seq., are very important. Essentially these results (ignoring dissipation to the bath) allow one to calculate the escape rate and so the quantum corrections to the magnetization relaxation time for axially symmetric potentials of the magnetocrystalline anisotropy. The foregoing results are also important in the inclusion of dissipation in the calculation of the relaxation time because due to the axial symmetry all that is required to write down such an equation is a knowledge of the stationary distribution as that entirely determines the diffusion coefficients since the precession term drops out of the Liouville operator.
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Towards universal quantum computation through relativistic motion

Towards universal quantum computation through relativistic motion

We have shown that it is possible to generate continuous-variable cluster states on electromagnetic cavity modes by choosing a suitable relativistic motion of the cavity. The entanglement grows linearly in time. The size of the lattice is determined by the choice of initial driving frequency, the amount of entanglement required between every mode and the desired length-to-height ratio of the square cluster. As a first experimental implementation, we propose a simple example of a four-mode square cluster state in a superconducting resonator with tuneable boundary con- ditions. This scheme is within reach of current circuit QED technology and would be the first demonstration of a multipartite continuous variable cluster state in cQED. An interesting avenue of research would be the extension to regimes of high squeezing levels, such as the ones required for fault-tolerant quantum computing with CV cluster states 37 . In brief, our main contribution is to implement cluster states in relativistic quantum field theory, paving
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Towards universal quantum computation through relativistic motion

Towards universal quantum computation through relativistic motion

We have shown that it is possible to generate continuous-variable cluster states on electromagnetic cavity modes by choosing a suitable relativistic motion of the cavity. he entanglement grows linearly in time. he size of the lattice is determined by the choice of initial driving frequency, the amount of entanglement required between every mode and the desired length-to-height ratio of the square cluster. As a irst experimental implementation, we propose a simple example of a four-mode square cluster state in a superconducting resonator with tuneable boundary con- ditions. his scheme is within reach of current circuit QED technology and would be the irst demonstration of a multipartite continuous variable cluster state in cQED. An interesting avenue of research would be the extension to regimes of high squeezing levels, such as the ones required for fault-tolerant quantum computing with CV cluster states 37 . In brief, our main contribution is to implement cluster states in relativistic quantum ield theory, paving
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Laser Cooling of an Optomechanical Crystal Resonator to Its Quantum Ground State of Motion

Laser Cooling of an Optomechanical Crystal Resonator to Its Quantum Ground State of Motion

In the measurements of this work, the same optical laser beam used to cool the mechanical oscillator is also used to detect its mechanical motion. Photodetection of the transmitted cooling beam and the light scattered by the mechanical oscillator produce a heterodyne output signal proportional to the mechanical motion. This also means that fluctuations in the cooling laser beam input that are imprinted into the mechanical system, are also read out by a beam containing the same fluctuations. In addition to potentially raising the phonon number beyond the quantum-backaction limit (in the case of added technical laser noise beyond shot noise), noise on the input cooling beam can also lead to a coherent cancellation effect at the readout called “noise squashing” which may cause the mechanical mode occupation to be inferred incorrectly (note that this effect can also be understood in terms of the recently demonstrated electromagnetically induced transparency (EIT), whereby noise photons are transmitted and/or reflected through a transparency window created by the cooling beam). Noise squashing has been studied in low-frequency mechanical systems, where excess laser phase noise can be an issue, and in recent microwave work where the electromagnetic cavity is populated with residual photons [49].
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Subwavelength Fabry Perot resonator: a pair of quantum dots incorporated with gold nanorod

Subwavelength Fabry Perot resonator: a pair of quantum dots incorporated with gold nanorod

30 nm) versus wavelength are plotted in Figure 7a according to Equation 3. The α value of each longitu- dinal mode of GNR with different ARs (4 to 8) is also plotted for comparison. The results show that these modes of GNR exhibit a correlation to the dispersion re- lation of GNW. In addition, the decay length ð 1=k 00 Þ of GNW and the apparent quantum yield, η ¼ P r = ð P r þ P nr Þ,

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Fractal Approximation of Motion and Its Implications in Quantum Mechanics

Fractal Approximation of Motion and Its Implications in Quantum Mechanics

Inconsistencies of some standard quantum mechanical models (Madelung’s, de Broglie’s models) are eliminated as- suming the micro particle movements on continuous, but non-differentiable curves (fractal curves). This hypothesis, named by us the fractal approximation of motion, will allow an unitary approach of the phenomena in quantum me- chanics (separation of the physical motion of objects in wave and particle components depending on the scale of resolu- tion, correlated motions of the wave and particle, i.e. wave-particle duality, the mechanisms of duality, by means of both phase wave-particle coherence and wave-particle incoherence, the particle as a clock, particle incorporation into the wave and the implications of such a process). Moreover, correspondences with standard gravitational models (Ein- stein’s model, string theory) can be also distinguished.
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Unstable Mechanical Objects: Motion Control, Stabilization

Unstable Mechanical Objects: Motion Control, Stabilization

stabilize a desired working regime of a discussed object is constructed in such a way that all resources of the control are used for suppressing unstable modes of motion. Such method of control law design provides maximal basin of attraction of the desired working regime. Problems of both local and global stabilization are investigated in the paper. When solving global stabilization problems, it is necessary to construct essentially nonlinear control functions. Optimal control and optimal trajectories are designed for some problems. The time-optimal control is designed using Pontryagin maximum principle. The optimal control is obtained in form of feedback. In some cases, intuitive consideration is used to create a control law.
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No evidence for DPOAEs in the mechanical motion of the locust tympanum

No evidence for DPOAEs in the mechanical motion of the locust tympanum

In previous experiments the acoustic presence of DPOAEs recorded from the locust ear suggested that the organ possesses non-linear hearing derived from active and mechanical non-linearities (Kössl and Boyan, 1998; Möckel et al., 2007). Complex sound processing in the locust ear has been known for some time; it is one of the few insect auditory organs known to be capable of frequency discrimination and having specific groups of cells for particular frequency ranges (Gray, 1960; Michelsen, 1971a). Regardless of this, the organ was previously considered to be a linear system (Breckow and Sippel, 1985; Michelsen, 1971b; Michelsen, 1971c). It was thought that all insect tympanal organs functioned passively through the mechanical motion of the membrane as no non-linear
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A Study of Entanglement and Squeezing of

A Study of Entanglement and Squeezing of

We organize the rest of this paper as follows. In section 2, the initial spin coherent state is introduced and its uncertainty aspects are discussed. Then, its time evolution via Hamiltonian (1) is considered and time dependent spin operators are obtained. Time depen- dence of the squeezing parameters (2) and (3) are also discussed in section 2. In section 3, entanglement parameters, their time dependence and their relationship to the squeezing parameters, are considered. Finally, section 4 is devoted to discussion and conclusions.

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A Lévy-Ciesielski expansion for quantum Brownian motion and the construction of quantum Brownian bridges

A Lévy-Ciesielski expansion for quantum Brownian motion and the construction of quantum Brownian bridges

variables” and “quantum stochastic processes”. The usual theory of such processes was established in a well-known paper by Accardi, Frigerio and Lewis ([1]). At its heart is the notion of a quantum random variable as an algebra homomorphism from a “state space algebra” into a “probability space algebra.” This generalises the fact that every classical random variable X defined on a probability space (Ω, F, P ) and taking values in a measurable space (U, U ) gives rise to a homomorphism j from the algebra B b (U) of

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Cold Electron Quantum Mechanical Model for Superconductivity

Cold Electron Quantum Mechanical Model for Superconductivity

On the other hand, recall that particular favor has paid on wave quantum mechanics; we have been intoxicated and paralyzed by the aura of quantum mechanics. Is the superconducting that make us wake up, let us see clearly the limitation of the traditional quantum mechanics. It make us to rethink why can the Bohr atomic model explain the hydrogen spectral series accurately to be regarded as a wrong thing at starting point, complain why we have to temporarily abandon the description of pure wave quantum mechanics for explaining the general dispersion force between all of molecules, worry the unsolved physical mechanism of the formation of light polarizability and the elliptic polarization, and look back the embarrassed issue we faced in electron spin. So, if a direct answer must be given, it seems that, as to the explanation of uncertainty relation, Heisenberg was right, and Earl Kennard would be wrong.
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The Bloch point in uniaxial ferromagnets as a quantum mechanical object

The Bloch point in uniaxial ferromagnets as a quantum mechanical object

Mesoscopic magnetic systems in ferromagnets with a uniaxial magnetic anisotropy are nowadays the subject of considerable attention both theoretically and experimen- tally. Among these systems are distinguished, especially domain walls (DWs) and elements of its internal structure - vertical Bloch lines (BLs; boundaries between domain wall areas with an antiparallel orientation of magnetization) and Bloch points (BPs; intersection point of two BL parts) [1]. The vertical Bloch lines and BPs are stable nanoformation with characteristic size of approximately 10 2 nm and considered as an elemental base for magnetoelectronic and solid-state data-storage devices on the magnetic base with high performance (mechanical stability, radiation resistance, non-volatility) [2]. The magnetic structures similar to BLs and BPs are also present in nanostripes and cylindrical nanowires [3-6], which are perspective materials for spintronics.
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A semiclassical approach to quantum Brownian motion in Wigner's phase space

A semiclassical approach to quantum Brownian motion in Wigner's phase space

Now, all of the above time evolution equations for the reduced density operator may be equivalently treated using the Wigner-Moyal phase space representation of quantum me­ chanics, thus[r]

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Leakage  Squeezing  of  Order  Two

Leakage Squeezing of Order Two

So, in front of leakage squeezing, not only the attacker shall conduct an attack of much higher order, but also she will get a very degraded distinguisher value. On n = 4 bits, the optimal first-order leakage squeezing is linear and allows to reach resistance order of 3. The used optimal code is [8, 4, 4]. For the second-order leakage squeezing, we can resort to the linear code [12, 4, 6], that improves by two (6 − 4 = 2) orders (with only one additional mask) the resistance against HO- CPA. By the trivial construct of Sec. 3.4, only one additional order of resistance would have been gained. A summary of the results is shown in Tab. 2. The improvement from the “straightforward” to the “squeezed” masking is of two orders with one mask and three orders with two masks.
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A Survey Paper on Microelectro Mechanical Beam Filters and Design of Clamped-Free Beam Resonator

A Survey Paper on Microelectro Mechanical Beam Filters and Design of Clamped-Free Beam Resonator

ABSTRACT: The need for different applications leads to various kinds of filter designs and numerous scaling techniques are used. This paper illustrates the basic principle of working of Microelectromechanical resonator which is fundamental part of filter. This resonator can be used in oscillator and filter. This paper also includes the results from the simulation of clamped free beam resonator in COMSOL multiphysics.

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The Quantum Mechanical Sensitivity of Cell Hydration in Mammals

The Quantum Mechanical Sensitivity of Cell Hydration in Mammals

The elucidation of the mechanism on the biological effects of weak chemical and physical factors on cells and organism is one of the modern problems in life sciences. According to the Receptor Theory of Prof. Bernard Katz the im- pact of the biological substances on cells is realized through the activation of ligand-gated ion channels in the membrane. However, this theory doesn’t provide a satisfactory explanation on the similar biological effects of extremely low concentrations of different chemical substances, which are unable to acti- vate the ionic channels in the membrane and have non-linear dose-dependent effect on cells. Previously we have suggested that the metabolic control of cell hydration serves as a universal quantum-mechanical sensor for different weak physical and chemical signals. For supporting this hypothesis, in this article the comparative study of the effects of low concentrations of both cold (non-radioactive) and [ 3 H]-ouabain (specific inhibitor for Na + /K + -ATPase) on
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