A bulk-optics, polarization-independent phase shifter for photonic quantum information applicatio... more A bulk-optics, polarization-independent phase shifter for photonic quantum information applications is demonstrated. A transverse mode electro-optic modulator using lithium niobate is placed in a Sagnac-like loop containing Faraday rotators. This direction-dependent polarization rotation in the loop is combined with a Mach-Zehnder interferometer to form an optical switch with an on/off contrast of 96% and a switching time of 1.6 ns.
Fourier transform has been shown to be a powerful tool in many area of science. However, there is... more Fourier transform has been shown to be a powerful tool in many area of science. However, there is another class of unitary transforms, the wavelet transforms, which are as useful as the Fourier transform. Wavelet transforms are used to expose the multi-scale structure of a signal and very useful for image processing and data compression. In this paper, we construct quantum algorithms for Haar wavelet transforms and show its application in analyzing the multi-scale structure of the dynamical system by the Logistic Map (x→ λx(1− x)), where λ takes value in the interval [0, 4).
We present numerical data showing, that three qutrit correlations for a pure state, which is not ... more We present numerical data showing, that three qutrit correlations for a pure state, which is not maximally entangled, violate local realism more strongly than three-qubit correlations. The strength of violation is measured by the minimal amount of noise that must be admixed to the system so that the noisy correlations have a local and realistic model.
Fourier transform has been shown to be a powerful tool in many area of science. However, there is... more Fourier transform has been shown to be a powerful tool in many area of science. However, there is another class of unitary transforms, the wavelet transforms, which are as useful as the Fourier transform. Wavelet transforms are used to expose the multi-scale structure of a signal and ...
Switching light on a time scale below 1 ns is a core building block of many photonic devices. How... more Switching light on a time scale below 1 ns is a core building block of many photonic devices. However most optical communication applications are not required to do this in a polarization independent manner, and can tolerate large insertion losses. For implementing quantum logic operations using the polarization of photons as information carriers, a low loss switch leaving the polarization of the photon untouched opens a new range of applications: conditional measurement schemes, combined polarization state, time bin encoding and quantum computing with optical qubits[1]. The obvious choice of using a simple mechanical mirror for phase shifting is limited by the inertia of the optical element, making this approach impractical for switching times below one microsecond.
A bulk-optics, polarization-independent phase shifter for photonic quantum information applicatio... more A bulk-optics, polarization-independent phase shifter for photonic quantum information applications is demonstrated. The device is based on a transverse electro-optic modulator in a Sagnac-type loop containing Faraday rotators. This direction-dependent polarization rotation in the loop is combined with a Mach–Zehnder interferometer to form an optical switch with an on/off contrast of 96% and a switching time of 1.6 ns. We demonstrate that the device's operation maintains any arbitrary polarization state.
We study the multiparticle generalized GHZ states. It has been shown that for an odd number of qu... more We study the multiparticle generalized GHZ states. It has been shown that for an odd number of qubits and for a specific range of parameters, they do not violate any Bell inequality for correlation functions. We show here both analytically and numerically that, nevertheless, such states violate local realism, once a more detailed analysis of the correlations is made than the one allowed by correlation functions. The results imply that multiparticle Clauser-Horne-type inequalities involving probabilities are stronger tools for analyzing violations of local realism in multiparticle systems than inequalities involving the correlation functions.
We present numerical data showing, that three qutrit correlations for a pure state, which is not ... more We present numerical data showing, that three qutrit correlations for a pure state, which is not maximally entangled, violate local realism more strongly than three-qubit correlations. The strength of violation is measured by the minimal amount of noise that must be admixed to the system so that the noisy correlations have a local and realistic model.
Quantum cryptography has become the first application of quantum mechanics at the single-quantum ... more Quantum cryptography has become the first application of quantum mechanics at the single-quantum level. During the last few years several studies have proven that distribution of secret keys over long distance using either faint laser pulses [2,3] (BB84 protocol [4]) or entangled photon pairs [5] (using Ekert protocol [1] or some more efficient protocols eg [6]) is possible. Recent studies have shown that systems using optical fibers as quantum channel are suitable for secret key distribution up to 100 km. In order to increase this limit proposals have been made to ...
A bulk-optics, polarization-independent phase shifter for photonic quantum information applicatio... more A bulk-optics, polarization-independent phase shifter for photonic quantum information applications is demonstrated. A transverse mode electro-optic modulator using lithium niobate is placed in a Sagnac-like loop containing Faraday rotators. This direction-dependent polarization rotation in the loop is combined with a Mach-Zehnder interferometer to form an optical switch with an on/off contrast of 96% and a switching time of 1.6 ns.
Fourier transform has been shown to be a powerful tool in many area of science. However, there is... more Fourier transform has been shown to be a powerful tool in many area of science. However, there is another class of unitary transforms, the wavelet transforms, which are as useful as the Fourier transform. Wavelet transforms are used to expose the multi-scale structure of a signal and very useful for image processing and data compression. In this paper, we construct quantum algorithms for Haar wavelet transforms and show its application in analyzing the multi-scale structure of the dynamical system by the Logistic Map (x→ λx(1− x)), where λ takes value in the interval [0, 4).
We present numerical data showing, that three qutrit correlations for a pure state, which is not ... more We present numerical data showing, that three qutrit correlations for a pure state, which is not maximally entangled, violate local realism more strongly than three-qubit correlations. The strength of violation is measured by the minimal amount of noise that must be admixed to the system so that the noisy correlations have a local and realistic model.
Fourier transform has been shown to be a powerful tool in many area of science. However, there is... more Fourier transform has been shown to be a powerful tool in many area of science. However, there is another class of unitary transforms, the wavelet transforms, which are as useful as the Fourier transform. Wavelet transforms are used to expose the multi-scale structure of a signal and ...
Switching light on a time scale below 1 ns is a core building block of many photonic devices. How... more Switching light on a time scale below 1 ns is a core building block of many photonic devices. However most optical communication applications are not required to do this in a polarization independent manner, and can tolerate large insertion losses. For implementing quantum logic operations using the polarization of photons as information carriers, a low loss switch leaving the polarization of the photon untouched opens a new range of applications: conditional measurement schemes, combined polarization state, time bin encoding and quantum computing with optical qubits[1]. The obvious choice of using a simple mechanical mirror for phase shifting is limited by the inertia of the optical element, making this approach impractical for switching times below one microsecond.
A bulk-optics, polarization-independent phase shifter for photonic quantum information applicatio... more A bulk-optics, polarization-independent phase shifter for photonic quantum information applications is demonstrated. The device is based on a transverse electro-optic modulator in a Sagnac-type loop containing Faraday rotators. This direction-dependent polarization rotation in the loop is combined with a Mach–Zehnder interferometer to form an optical switch with an on/off contrast of 96% and a switching time of 1.6 ns. We demonstrate that the device's operation maintains any arbitrary polarization state.
We study the multiparticle generalized GHZ states. It has been shown that for an odd number of qu... more We study the multiparticle generalized GHZ states. It has been shown that for an odd number of qubits and for a specific range of parameters, they do not violate any Bell inequality for correlation functions. We show here both analytically and numerically that, nevertheless, such states violate local realism, once a more detailed analysis of the correlations is made than the one allowed by correlation functions. The results imply that multiparticle Clauser-Horne-type inequalities involving probabilities are stronger tools for analyzing violations of local realism in multiparticle systems than inequalities involving the correlation functions.
We present numerical data showing, that three qutrit correlations for a pure state, which is not ... more We present numerical data showing, that three qutrit correlations for a pure state, which is not maximally entangled, violate local realism more strongly than three-qubit correlations. The strength of violation is measured by the minimal amount of noise that must be admixed to the system so that the noisy correlations have a local and realistic model.
Quantum cryptography has become the first application of quantum mechanics at the single-quantum ... more Quantum cryptography has become the first application of quantum mechanics at the single-quantum level. During the last few years several studies have proven that distribution of secret keys over long distance using either faint laser pulses [2,3] (BB84 protocol [4]) or entangled photon pairs [5] (using Ekert protocol [1] or some more efficient protocols eg [6]) is possible. Recent studies have shown that systems using optical fibers as quantum channel are suitable for secret key distribution up to 100 km. In order to increase this limit proposals have been made to ...
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Papers by Darwin Gosal