We construct quantum gate entangler for general multipartite states based on topological unitary operators. We show that these operators can entangle quantum states if they satisfy the separability condition that is given by the complex multi-projective Segre variety. We also in detail discuss the construction of quantum gate entangler for higher dimensional bipartite and three-partite quantum ...

Experimental realization of quantum information processing in the field of nuclear magnetic resonance (NMR) has been well established. Implementation of conditional phase-shift gate has been a significant step, which has lead to realization of important algorithms such as Grover's search algorithm and quantum Fourier transform. This gate has so far been implemented in NMR by using coupling evol...

Chakrabarti Group (J. Quantum Information) Abstract Quantum gates are usually executed by gate decomposition strategies that apply specifically designed Hamiltonians sequentially to generate the desired overall time evolution. However, the desired time evolution can also be achieved via optimal control methods, wherein shaped electromagnetic fields generate motion in the directions necessary to...

All-optical switching is a technique in which a gate light pulse changes the transmission of a target light pulse without the detour via electronic signal processing. We take this to the quantum regime, where the incoming gate light pulse contains only one photon on average. The gate pulse is stored as a Rydberg excitation in an ultracold atomic gas using electromagnetically induced transparenc...

A crucial building block for quantum information processing with trapped ions is a controlledNOT quantum gate. In this paper, two different sequences of laser pulses implementing such a gate operation are analyzed using quantum process tomography. Fidelities of up to 92.6(6) % are achieved for single gate operations and up to 83.4(8) % for two concatenated gate operations. By process tomography...

Among the many proposals for the realization of a quantum computer, holonomic quantum computation is distinguished from the rest as it is geometrical in nature and thus expected to be robust against decoherence. Here we analyze the realization of various quantum gates by solving the inverse problem: Given a unitary matrix, we develop a formalism by which we find loops in the parameter space gen...

It is generally believed that entanglement speeds up Quantum Information Processing (QIP). However, we prove that for a system of two interacting qubits through a XXZ Hamiltonian which are maximally entangled it is not possible to execute a quantum NOT gate operating on one of these two qubits. The interaction between the two qubits means presence of noise in one of them. If the two interacting...

It is generally believed that entanglement speeds up Quantum Information Processing (QIP). However, we prove that for a system of two interacting qubits through a XXZ Hamiltonian which are maximally entangled it is not possible to execute a quantum NOT gate operating on one of these two qubits. The interaction between the two qubits means presence of noise in one of them. If the two interacting...

Universal multiple-qubit gates can be implemented by a set of universal single-qubit gates and any one kind of entangling two-qubit gate, such as a controlled-NOT gate. For semiconductor quantum dot qubits, two-qubit gate operations have so far only been demonstrated in individual electron spin-based quantum dot systems. Here we demonstrate the conditional rotation of two capacitively coupled c...