共查询到20条相似文献,搜索用时 15 毫秒
1.
Biosensors based on the shift of whispering-gallery modes in microspheres accompanying protein adsorption are described by use of a perturbation theory. For random spatial adsorption, theory predicts that the shift should be inversely proportional to microsphere radius R and proportional to protein surface density and excess polarizability. Measurements are found to be consistent with the theory, and the correspondence enables the average surface area occupied by a single protein to be estimated. These results are consistent with crystallographic data for bovine serum albumin. The theoretical shift for adsorption of a single protein is found to be extremely sensitive to the target region, with adsorption in the most sensitive region varying as 1/R(5/2). Specific parameters for single protein or virus particle detection are predicted. 相似文献
2.
Lermer M Gregersen N Dunzer F Reitzenstein S Höfling S Mørk J Worschech L Kamp M Forchel A 《Physical review letters》2012,108(5):057402
We have employed Bloch-wave engineering to realize submicron diameter high quality factor GaAs/AlAs micropillars (MPs). The design features a tapered cavity in which the fundamental Bloch mode is subject to an adiabatic transition to match the Bragg mirror Bloch mode. The resulting reduced scattering loss leads to record-high vacuum Rabi splitting of the strong coupling in MPs with modest oscillator strength quantum dots. A quality factor of 13,?600 and a splitting of 85 μeV with an estimated visibility v of 0.41 are observed for a small mode volume MP with a diameter d{c} of 850 nm. 相似文献
3.
We experimentally realize a Fabry-Perot-type optical microresonator near the cesium D2 line wavelength based on a tapered optical fiber, equipped with two fiber Bragg gratings that enclose a subwavelength diameter waist. Owing to the very low taper losses, the finesse of the resonator reaches F=86 while the on-resonance transmission is T=11%. The characteristics of our resonator fulfill the requirements of nonlinear optics and cavity quantum electrodynamics in the strong coupling regime. These characteristics, combined with the demonstrated ease of use and advantageous mode geometry, open a realm of applications. 相似文献
4.
Pigtailing the high-Q microsphere cavity: a simple fiber coupler for optical whispering-gallery modes 总被引:5,自引:0,他引:5
We demonstrate a simple method for efficient coupling of standard single-mode optical fibers to a high- Q optical microsphere cavity. Phase-matched excitation of whispering-gallery modes is provided by an angle-polished fiber tip in which the core-guided wave undergoes total internal reflection. In the experimental setup, which included a microsphere with both an input and an output coupler, the total fiber-to-fiber transmission at resonance reached 23% (total insertion loss, 6.3 dB), with loaded quality factor Q>/=3x10(7) and unloaded Q approximately 1.2x10(8) at 1550 nm. A simple pigtailing method for microspheres permits their wider use in fiber optics and photonics devices. 相似文献
5.
A quantum mechanical superposition of a long-lived, localized phonon and a matter excitation is described. We identify a realization in strained silicon: a low-lying donor transition (P or Li) driven solely by acoustic phonons at wavelengths where high-Q phonon cavities can be built. This phonon-matter resonance is shown to enter the strongly coupled regime where the "vacuum" Rabi frequency exceeds the spontaneous phonon emission into noncavity modes, phonon leakage from the cavity, and phonon anharmonicity and scattering. We introduce a micropillar distributed Bragg reflector Si/Ge cavity, where Q?10(5)-10(6) and mode volumes V?25λ(3) are reachable. These results indicate that single or many-body devices based on these systems are experimentally realizable. 相似文献
6.
We demonstrate mid-infrared spectroscopy of large molecules with broad absorption features using a tunable external cavity quantum cascade laser. Absorption spectra for two different Freons are measured over the range 1130-1185 cm(-1) with 0.2 cm(-1) resolution via laser photoacoustic spectroscopy with quartz tuning forks as acoustic transducers. The measured spectra are in excellent agreement with published reference absorption spectra. 相似文献
7.
A three-level atom in a Λ configuration trapped in an optical cavity forms a basic unit in a number of proposed protocols
for quantum information processing. This system allows for efficient storage of cavity photons into long-lived atomic excitations,
and their retrieval with high fidelity, in an adiabatic transfer process through the ‘dark state’ by a slow variation of the
control laser intensity. We study the full quantum mechanics of this transfer process with a view to examine the non-adiabatic
effects arising from inevitable excitations of the system to states involving the upper level of Λ, which is radiative. We
find that the fidelity of storage is better, the stronger the control field and the slower the rate of its switching off.
On the contrary, unlike the adiabatic notion, retrieval is better with faster rates of switching on of an optimal control
field. Also, for retrieval, the behaviour with dissipation is non-monotonic. These results lend themselves to experimental
tests. Our exact computations, when applied to slow variations of the control intensity for strong atom–photon couplings,
are in very good agreement with Berry’s superadiabatic transfer results without dissipation. 相似文献
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10.
Scheme for implementing perfect quantum teleportatior with four-qubit entangled states in cavity quantum electrodynamics 下载免费PDF全文
Recently, Peng et al. [2010 Eur. Phys. J. D 58 403] proposed to teleport an arbitrary two-qubit state with a family of four-qubit entangled states, which simultaneously include the tensor product of two Bell states, linear cluster state and Dicke-class state. This paper proposes to implement their scheme in cavity quantum electrodynamics and then presents a new family of four-qubit entangled state |Ω/1234. It simultaneously includes all the well-known four-qubit entangled states which can be used to teleport an arbitrary two-qubit state. The distinct advantage of the scheme is that it only needs a single setup to prepare the whole family of four-qubit entangled states, which will be very convenient for experimental realization. After discussing the experimental condition in detail, we show the scheme may be feasible based on present technology in cavity quantum electrodynamics. 相似文献
11.
Efficient scheme for preparation of the multi-atom W state via cavity quantum electrodynamics 下载免费PDF全文
We present an efficient scheme for preparation of the multi-atom W state via cavity quantum electrodynamics. Involved in this scheme are n identical two-level atoms and a single-mode cavity field. Discussion indicates that this scheme can be realized easily by current technologies. 相似文献
12.
Scheme for implementing perfect quantum teleportation with four-qubit entangled states in cavity quantum electrodynamics 下载免费PDF全文
Recently, Peng et al. [2010 Eur. Phys. J. D 58 403] proposed to teleport an arbitrary two-qubit state with a family of four-qubit entangled states, which simultaneously include the tensor product of two Bell states, linear cluster state and Dicke-class state. This paper proposes to implement their scheme in cavity quantum electrodynamics and then presents a new family of four-qubit entangled state |Ω4>1234. It simultaneously includes all the well-known four-qubit entangled states which can be used to teleport an arbitrary two-qubit state. The distinct advantage of the scheme is that it only needs a single setup to prepare the whole family of four-qubit entangled states, which will be very convenient for experimental realization. After discussing the experimental condition in detail, we show the scheme may be feasible based on present technology in cavity quantum electrodynamics. 相似文献
13.
We investigate the single-photon transport problem in the system of a whispering-gallery mode microresonator chirally coupled with a two-level quantum emitter [QE). Conventionally, this chiral QE-microresonator coupling system can be studied by the master equation and the single-photon transport methods. Here, we provide a new approach, based on the transfer matrix, to assess the single-photon transmission of such a system. Furthermore, we prove that these three methods are equivalent. The corre... 相似文献
14.
《中国物理 B》2018,(12)
We theoretically study the collective decay of two atoms trapped in a single mode cavity and we describe the evolution of the population of Dicke states. We show that the collective decay property is strongly dependent on the phase of atomic radiation and the speeding up of collective decay can only be observed in a bad cavity regime. For in-or out-phase case,this occurs due to the quantum interference enhancement, no matter which atom is excited initially. For π/2 phase, the speeding up of collective decay takes place if the first atom is excited at the beginning. However, it disappears due to the quantum interference cancellation if the second atom is excited. Compared with the in-phase and out-phase cases,we also show that the speeding up of collective decay can be significantly enhanced in strong coupling regime for π/2 phase, although one atom is decoupled to the cavity in this condition. The study presented here is helpful to understand the physical mechanism of collective decay in cavity quantum electrodynamics and it provides a useful method to control the collective decay phenomenon via quantum interference effect. 相似文献
15.
Teleportation of two-atom entangled state in resonant cavity quantum electrodynamics 总被引:4,自引:0,他引:4 下载免费PDF全文
An alternative scheme is presented for teleportation of a two-atom
entangled state in cavity quantum electrodynamics (QED). It is based
on the resonant atom--cavity field interaction. In the scheme, only
one cavity is involved, and the number of the atoms needed to be
detected is decreased compared with the previous scheme. Since the
resonant atom--cavity field interaction greatly reduces the
interaction time, the decoherence effect can be effectively
suppressed during the teleportation process. The experimental
feasibility of the scheme is discussed. The scheme can easily be
generalized to the teleportation of N-atom
Greeninger--Horne--Zeilinger (GHZ) entangled states. The number of
atoms needed to be detected does not increase as the number of the
atoms in the GHZ state increases. 相似文献
16.
A scheme is proposed for generating entangled W states with four
cavity modes. In this scheme, we send a V-type three-level atom
through two identical two-mode cavities in succession. After the
atom exits from the second cavity, the four cavity modes are
prepared in the W state. On the other hand we can obtain
three-atom W states by sending three V-type three-level atoms
through a two-mode cavity in turn. The present scheme does not
require conditional measurement, and it is easily generalized to
preparing $2n$-mode W states and $n$-atom W states. 相似文献
17.
The ability to achieve near lossless coupling between a waveguide and a resonator is fundamental to many quantum-optical studies as well as to practical applications of such structures. The nature of loss at the junction is described by a figure of merit called ideality. It is shown here that under appropriate conditions ideality in excess of 99.97% is possible using fiber-taper coupling to high-Q silica microspheres. To verify this level of coupling, a technique is introduced that can both measure ideality over a range of coupling strengths and provide a practical diagnostic of parasitic coupling within the fiber-taper-waveguide junction. 相似文献
18.
A scheme for transferring an unknown atomic entangledstate via cavity quantum electrodynamics 下载免费PDF全文
In this paper, we propose a scheme for transferring an unknown atomic entangled
state via cavity quantum electrodynamics (QED). This scheme, which has a successful
probability of 100 percent, does not require Bell-state measurement and performing
any operations to reconstruct an initial state. Meanwhile, the scheme only involves
atom--field interaction with a large detuning and does not require the transfer of
quantum information between the atoms and cavity. Thus the scheme is insensitive to
the cavity field states and cavity decay. This scheme can also be extended to
transfer ring an entangled state of $n$-atom. 相似文献
19.
《中国光学快报(英文版)》2017,(5)
We investigate the transitions between energy levels and parity symmetry in an effective two-level polar molecule system strongly coupled with a quantized harmonic oscillator. By the dressed-state perturbation theory,the transition diagrams between the dressed-state energy levels are presented clearly and show that the odd(even) parity symmetry is broken by the permanent dipole moment(PDM) of the polar molecules. By the analytical and numerical methods, we find that when the coupling strength and the PDM increase, the more frequency components are induced by the counter-rotating terms and PDM. 相似文献
20.
研究了三个全同二能级原子与单模腔相互作用系统中原子间的三体纠缠特性.考虑原子间存在相互耦合,并且腔场处于弱相干态的情况,通过数值计算给出了纠缠量的演化曲线,讨论了原子间耦合强度和弱相干场强度对三体纠缠的影响.研究结果表明:随弱相干场强度增强,原子间的三体纠缠增强;相反,随原子间耦合系数增大,原子间三体纠缠减弱. 相似文献