Abstract

A novel method of lock-in elimination using electro-optic phase modulator in semiconductor ring laser gyroscope is proposed. It helps in operating the gyro out of the lock-in band, thus improving its sensitivity.

Abstract

Conservative coupling of modes in an integrated external-cavity semiconductor ring laser is used to suppress lock-in in an inertial rotation sensor. Extent of suppression is dependent on refractive index difference between active and passive cavities.

Abstract

In this paper, biotin streptavidin interaction has been sensed at microwave frequencies with the help of designed sensor. It takes advantage of two pole filter topology where interdigitated capacitor (IDC) is used as a coupling zone between resonators for higher sensitivity. Due to permittivity change of biotin streptavidin combination, shift in resonant frequency arise whereas due to conductivity, magnitude of reflection coefficient changes. The frequency range of 10 GHz - 25 GHz (γ-dispersion region) is used as it is effective for label free analysis of biotin streptavidin. Due to homogeneous E-field between the fingers of IDC, placement position of biotin-streptavidin will not affect the sensitivity. Significant frequency shifts as high as 19 MHz, 45 MHz and 70 MHz are observed for concentrations as low as 10 ng/ml, 20 ng/ml and 30 ng/ml of biotin-streptavidin respectively. Simulation results suggest that proposed biosensor …

Abstract

CMOS Schmitt trigger is a widely used hysteretic device due to its noise immunity. However, hysteresis by itself incorporate a delay in the device. In order to eliminate the problem of delay and advance the transition, we propose a circuit which works on the principle of proteresis. It is similar to hysteresis but has reverse behavior. Theoretically, when compared to an hysteretic bistable device, a proteretic device has a swapped triggering voltages which leads to twofold speed without altering the ability of noise immunity. The simulation results demonstrate an improvement of approximately 140% in transition time delay when compared to the Schmitt trigger at the cost of area and could be further improved by proper sizing. By using UMC 180 nm CMOS technology, a 0.2 V width proteretic loop has been achieved which signifies the amount of noise immunity it possesses.

Abstract

We introduce a new feature of no-signaling (Bell) non-local theories, namely, when a system of multiple parties manifests genuine non-local correlation, then there cannot be arbitrarily high nonlocal correlation among any subset of the parties. We call this feature, complementarity of genuine multipartite non-locality. We use Svetlichny’s criterion for genuine multipartite non-locality and nonlocal games to derive the complementarity relations under no-signaling constraints. We find that the complementarity relations are tightened for the much stricter quantum constraints. We compare this notion with the well-known notion of monogamy of non-locality. As a consequence, we obtain tighter non-trivial monogamy relations that take into account genuine multipartite non-locality. Furthermore, we provide numerical evidence showcasing this feature using a bipartite measure and several other well-known tripartite measures of non-locality.

Abstract

In this work we give a (n, n)-threshold protocol for sequential secret sharing of quantum information for the first time. By sequential secret sharing we refer to a situation where the dealer is not having all the secrets at the same time, at the beginning of the protocol; however if the dealer wishes to share secrets at subsequent phases she/he can realize it with the help of our protocol. First of all we present our protocol for three parties and later we generalize it for the situation where we have more (n > 3) parties. Interestingly, we show that our protocol of sequential secret sharing requires less amount of quantum as well as classical resource as compared to the situation wherein existing protocols are repeatedly used. Further in a much more realistic situation, we consider the sharing of qubits through two kinds of noisy channels, namely the phase damping channel (PDC) and the amplitude damping channel (ADC). When we carry out the sequential secret sharing in the presence of noise we observe that the fidelity of secret sharing at the kth iteration is independent of the effect of noise at the (k − 1)th iteration. In case of ADC we have seen that the average fidelity of secret sharing drops down to 1 2 which is equivalent to a random guess of the quantum secret. Interestingly, we find that by applying weak measurements one can enhance the average fidelity. This increase of the average fidelity can be achieved with certain trade off with the success probability of the weak measurements

Abstract

Complementarity have been an intriguing feature of physical systems for a long time. In this work we establish a new kind of complimentary relations in the frame work of quantum information processing tasks. In broadcasting of entanglement we create many pairs of less entangled states from a given entangled state both by local and non local cloning operations. These entangled states can be used in various information processing tasks like teleportation and superdense coding. Since these states are less entangled states it is quite intuitive that these states are not going to be as powerful resource as the initial states. In this work we study the usefulness of these states in tasks like teleportation and super dense coding. More precisely, we found out bounds of their capabilities in terms of several complimentary relations involving fidelity of broadcasting. In principle we have considered general mixed as a resource also separately providing different examples like a) Werner like states, b) Bell diagonal states. Here we have used both local and non local cloning operations as means of broadcasting. In the later part of our work, we extend this result by obtaining bounds in form of complimentary relations in a situation where we have used 1 − N cloning transformations instead of 1 − 2 cloning transformations

Abstract

It has been suggested that there may exist quantum correlations that go beyond entanglement. The existence of such correlations can be revealed by information theoretic quantities such as quantum discord, but not by the conventional measures of entanglement. We argue that a state displays quantumness that can be of local and nonlocal origin. Information theoretic measures not only characterize the nonlocal quantumness but also the local quantumness, such as the “local superposition”. This can be a reason why such measures are nonzero when there is no entanglement. We consider a generalized version of the Werner state to demonstrate the interplay of local quantumness, nonlocal quantumness, and classical mixedness of a state.

Abstract

In a recent work, authors prove a yet another no-go theorem that forbids the existence of a universal probabilistic quantum protocol producing a superposition of two unknown quantum states. In this short note, we show that in the presence of closed time like curves, one can indeed create superposition of unknown quantum states and evade the no-go result.

Abstract

We find a single parameter family of genuinely entangled three qubit pure states, called the maximally Bell inequality violating states (MBV), which exhibit maximum Bell inequality violation by the reduced bipartite system for a fixed amount of genuine tripartite entanglement quantified by the so called tangle measure. This in turn implies that there holds a complementary relation between the Bell inequality violation by the reduced bipartite systems and the tangle present in the three qubit states, not necessarily pure. The MBV states also exhibit maximum Bell inequality violation by the reduced bipartite systems of the three qubit pure states with a fixed amount of genuine tripartite correlation quantified by the generalized geometric measure, a genuine entanglement measure of multiparty pure states, and the discord monogamy score, a multipartite quantum correlation measure from information theoretic paradigm. The aforementioned complementary relation has also been established for three qubit pure states for the generalized geometric measure and the discord monogamy score respectively. The complementarity between the Bell inequality violation by the reduced bipartite systems and the genuine tripartite correlation suggests that the Bell inequality violation in the reduced two qubit system comes at the cost of the total tripartite correlation present in the entire system.