A scheme for distributed quantum search through simultaneous state transfer mechanism

Abstract

Key words Distributed quantum computing, quantum algorithm, Grover's search algorithm. PACS 03.67.-a, 03.65.Ud, 03.67.LxUsing a quantum network model, we present a scheme for distributed implementation of Grover's algorithm. The proposed scheme can implement a quantum search over data bases stored in different computers. Entanglement is used to carry out different non-local operations over the spatially distributed quantum computers. A method to transfer the combined state of many qubits over the entanglement and subsequently refreshing the entangled pair is presented. This method of simultaneous state transfer from one computer to the other, is shown to result in a constant communication complexity.

General structures of reversible and quantum gates

“…However, in the traditional irreversible computing, some losses of energy would still happen as it is implemented with irreversible logic gates, like AND, NOR, NAND all of which map a 2-bit input into a 1-bit output and thus causes an energy loss amounting to at least kT ln 2. This advantage of reversible computing and the computational speed up achieved by the quantum computer have motivated scientists to design and optimize reversible and quantum circuits for various purposes [for a set of interesting reversible circuits see [8,9], some interesting reversible circuits and their optimization are reported in [10][11][12], whereas a set of important quantum circuits can be found at [13][14][15][16][17][18][19]]. All these circuits are designed using gates represented by unitary operations, but the general structure of those unitary operations is not investigated until today.…”

Protocols and quantum circuits for implementing entanglement concentration in cat state, GHZ-like state and nine families of 4-qubit entangled states

“…In general, the amount of entanglement is usually reduced during transmission process. Unfortunately, such degradation of entanglement is unavoidable, but for the proper execution of the protocols mentioned above [2][3][4][5][6][7][8] we need perfect quantum channels for distribution of ebits. In absence of such a channel it would be sufficient to design a protocol that can convert the non-maximally entangled state back into maximally entangled state.…”

“…Entanglement plays a crucial role in quantum computation and quantum communication [1][2][3][4][5][6][7][8]. It is essential for realization of various protocols and algorithms [1][2][3][4][5][6][7][8].…”

“…Entanglement plays a crucial role in quantum computation and quantum communication [1][2][3][4][5][6][7][8]. It is essential for realization of various protocols and algorithms [1][2][3][4][5][6][7][8]. Specifically, maximally entangled state is required for realization of nonlocal quantum gates [1], distributed quantum search algorithm [2], teleportation [3], densecoding [4], entanglement based quantum key distribution [5] and entanglement based secure direct quantum communication [6][7][8].…”

“…It is essential for realization of various protocols and algorithms [1][2][3][4][5][6][7][8]. Specifically, maximally entangled state is required for realization of nonlocal quantum gates [1], distributed quantum search algorithm [2], teleportation [3], densecoding [4], entanglement based quantum key distribution [5] and entanglement based secure direct quantum communication [6][7][8]. In these applications, entanglement is generally produced locally and distributed to different parties involved in the communication or computation process.…”