DOI: 10.1002/adom.201801433 Scientific American selects plasmonic sensing as the top 10 emerging technologies of 2018.[15] Almost every single new plasmonic or photonic structure would be explored to test its sensing ability.[16–29] These works tend to report the sensing performance of their own structure. Some declare that their sensitivity breaks the world record. However, there is still a missing literature on what the world record really is, the gap between the experiments and the theoretical limit, as well as the differences between metal-based plasmonic sensors and dielectric-based photonic sensors. To push plasmonic and photonic sensors into industrial applications, an optical sensing technology map is absolutely necessary. This review aims to cover a wide range of most representative plasmonic and photonic sensors, and place them into a single map. The sensor performances of different structures will be distinctly illustrated. Future researchers could plot the sensing ability of their new sensors into this technology map and gauge their performances in this field. In this review, we focus on optical refractive index (RI) sensors with no fluorescent labeling required. We will utilize two parameters to characterize and compare the performance of optical RI sensors: sensitivity to RI change (denoted by symbol SRI) and figure of merit (in short, FoM). For simplicity, we restrict our discussions to bulk RI change, where the change in RI occurs within the whole sample. There is another case where the RI variation occurs only within a very small volume close to the sensor surface. This surface RI sensitivity is proportional to the bulk RI sensitivity, the ratio of the thickness of the layer within which the surface RI variation occurs, and the penetration depth of the optical mode.[6] The bulk RI sensitivity defines the ratio of the change in sensor output (e.g., resonance angle, intensity, or resonant wavelength) to the bulk RI variations. Here, we limit our discussions to the spectral interrogations and the bulk RI sensitivity SRI is given by[3,5–7,30]

Optical Refractive Index Sensors with Plasmonic and Photonic Structures: Promising and Inconvenient Truth

A theoretical scheme is proposed to implement bidirectional quantum controlled teleportation (BQCT) by using a nine-qubit entangled state as a quantum channel, where Alice may transmit an arbitrary two-qubit state called qubits $$A_1$$A1 and $$A_2$$A2 to Bob; and at the same time, Bob may also transmit an arbitrary two-qubit state called qubits $$B_1$$B1 and $$B_2$$B2 to Alice via the control of the supervisor Charlie. Based on our channel, we explicitly show how the bidirectional quantum controlled teleportation protocol works. And we show this bidirectional quantum controlled teleportation scheme may be determinate and secure. Taking the amplitude-damping noise and the phase-damping noise as typical noisy channels, we analytically derive the fidelities of the BQCT process and show that the fidelities in these two cases only depend on the amplitude parameter of the initial state and the decoherence noisy rate.

Bidirectional controlled teleportation by using nine-qubit entangled state in noisy environments

We present a scheme for bidirectional controlled teleportation by using a six-qubit cluster state as quantum channel. Based on the C-not operation and single qubit measurements, Alice may transmit an arbitrary single qubit state of qubit A to Bob and Bob may transmit an arbitrary single qubit state of qubit B to Alice via the control of the supervisor Charlie.

Bidirectional Controlled Teleportation via Six-Qubit Cluster State

In optics, the two main mechanisms for enhancing the Goos-H\"anchen (GH) shift of a reflected light beam have a common shortcoming: The maximum shift is located exactly at the reflectance dip, which makes the reflected beam hard to detect. Here the authors tune the excitation of guided modes in a compound grating-waveguide structure, to realize quasibound states in the continuum (quasi-BICs) with ultrahigh $Q$-factors. Assisted by these quasi-BICs, the GH shift at the reflectance peak can be greatly enhanced. This giant GH shift with high reflectance can be used for $e.g.$ ultrasensitive sensors, wavelength-division (de)multiplexers, optical switches, and polarization beam splitters.

Giant Enhancement of the Goos-Hänchen Shift Assisted by Quasibound States in the Continuum

A bidirectional quantum controlled teleportation scheme using a seven-qubit maximally entangled state as quantum channel is proposed. This means that Alice can transmit an arbitrary single qubit state of qubit a to Bob and Bob can transmit an arbitrary single qubit state of qubit b to Alice via the control of the supervisor Charlie.

Bidirectional Quantum Controlled Teleportation via a Maximally Seven-qubit Entangled State

A scheme is presented to implement bidirectional controlled quantum teleportation (QT) by using a five-qubit entangled state as a quantum channel, where Alice may transmit an arbitrary single qubit state called qubit A to Bob and at the same time, Bob may also transmit an arbitrary single qubit state called qubit B to Alice via the control of the supervisor Charlie. Based on our channel, we explicitly show how the bidirectional controlled QT protocol works. By using this bidirectional controlled teleportation, espcially, a bidirectional controlled quantum secure direct communication (QSDC) protocol, i.e., the so-called controlled quantum dialogue, is further investigated. Under the situation of insuring the security of the quantum channel, Alice (Bob) encodes a secret message directly on a sequence of qubit states and transmits them to Bob (Alice) supervised by Charlie. Especially, the qubits carrying the secret message do not need to be transmitted in quantum channel. At last, we show this QSDC scheme may be determinate and secure.

Bidirectional controlled quantum teleportation and secure direct communication using five-qubit entangled state

A new application of the four-qubit cluster state is investigated for quantum information splitting (QIS) of an arbitrary three-qubit state. Muralidharan and Panigrahi (Phys Rev A 78:062333, 2008) argued that a four-qubit cluster state is impossible for QIS of an arbitrary two-qubit state. In this paper, we demonstrate that two four-qubit cluster states can be used to realize the deterministic QIS of an arbitrary three-qubit state by performing only the Bell-state measurements. Our scheme considered here is secure against certain eavesdropping attacks.

Quantum information splitting of an arbitrary three-qubit state by using two four-qubit cluster states

Quantum state sharing of an arbitrary three-qubit state by using four sets of W-class states

By using a generalized Greenberger---Horne---Zeilinger (GHZ) state in which is locally unitarily connected with standard GHZ state as a communication channel, semi-quantum key distribution is extended to study semi-quantum information splitting protocols for secret sharing of quantum information. In our scheme, quantum Alice splits arbitrary two, three and N-qubit states with two classical parties, Bob and Charlie, in a way that both parties are sufficient to reconstruct Alice's original states only under the condition of which she/he obtains the help from another one, but one of them cannot. The presented protocols are helpful for both secure against certain eavesdropping attacks and economical in processing of quantum information.

Semi-quantum information splitting using GHZ-type states

We present a novel and simple optical structure, i.e., the symmetrical metal-cladding waveguide, in which a polymer layer is added into the guiding layer, for sensitive detection of chemical vapor by using the enhanced Goos-Hanchen (GH) shift (nearly a millimeter scale). Owing to the high sensitivity of the excited ultrahigh-order modes, the vapor-induced effect (swelling effect and refractive index change) in the polymer layer will lead to a dramatic variation of the GH shift. The detected GH shift signal is irrelevant to the power fluctuation of the incident light. The detection limit of 9.5 ppm for toluene and 28.5 ppm for benzene has been achieved.

Yi-you Nie

Papers

Bidirectional controlled quantum teleportation and secure direct communication using five-qubit entangled state

Quantum information splitting of an arbitrary three-qubit state by using two four-qubit cluster states

Quantum state sharing of an arbitrary three-qubit state by using four sets of W-class states

Semi-quantum information splitting using GHZ-type states

Detection of chemical vapor with high sensitivity by using the symmetrical metal-cladding waveguide-enhanced Goos-Hänchen shift