Decoherence and Fidelity of Single Qubit Operations in a Solid State Quantum Computer

2006 ◽  
pp. 247-250
Author(s):  
C. J. Wellard ◽  
L. C. L. Hollenberg
Keyword(s):  
Solid State ◽  
Quantum Computer ◽  
Single Qubit ◽  
Qubit Operations

SILICON-BASED NUCLEAR SPIN QUANTUM COMPUTER

2005 ◽  
Vol 03 (supp01) ◽  
pp. 27-40 ◽  
Author(s):  
HSI-SHENG GOAN
Keyword(s):  
Solid State ◽  
Nuclear Spin ◽  
Quantum Computer ◽  
Theoretical Progress ◽  
Spin Quantum ◽  
Basic Physics ◽  
Qubit Operations ◽  
Silicon Based

We review the basic physics and operation principles of the silicon-based quantum computer proposed by Kane, one of the most promising solid-state quantum computer proposals. We describe in some details how single- and two-qubit operations and readout measurements can, in principle, be performed for the Kane quantum computer. In addition, we also mention briefly its recent theoretical progress and development.

scholarly journals Solid-state Stern–Gerlach spin splitter for magnetic field sensing, spintronics, and quantum computing

2018 ◽  
Vol 9 ◽  
pp. 1558-1563 ◽  
Author(s):  
Kristofer Björnson ◽  
Annica M Black-Schaffer
Keyword(s):  
Solid State ◽  
Magnetic Flux ◽  
Quantum Computer ◽  
Characteristic Size ◽  
Two Dimensional ◽  
Interference Effects ◽  
Switching Field ◽  
Single Qubit ◽  
Field Sensitivity ◽  
Universal Quantum

We show conceptually that the edge of a two-dimensional topological insulator can be used to construct a solid-state Stern–Gerlach spin splitter. By threading such a Stern–Gerlach apparatus with a magnetic flux, Aharanov–Bohm-like interference effects are introduced. Using ferromagnetic leads, the setup can be used to both measure magnetic flux and as a spintronics switch. With normal metallic leads a switchable spintronics NOT-gate can be implemented. Furthermore, we show that a sequence of such devices can be used to construct a single-qubit SU(2)-gate, one of the two gates required for a universal quantum computer. The field sensitivity, or switching field, b, is related to the characteristic size of the device, r, through b = h/(2πqr 2), with q being the unit of electric charge.

Universal quantum computing in linear nearest neighbor architectures

2011 ◽  
Vol 11 (3&4) ◽  
pp. 300-312
Author(s):  
Preethika Kumar ◽  
Steven R. Skinner
Keyword(s):  
Quantum Computing ◽  
Solid State ◽  
Control Parameter ◽  
Nearest Neighbor ◽  
Quantum Computer ◽  
Gate Operation ◽  
One Dimensional ◽  
Single Qubit ◽  
Universal Quantum ◽  
Target Qubit

We introduce a scheme for realizing universal quantum computing in a linear nearest neighbor architecture with fixed couplings. We first show how to realize a controlled-NOT gate operation between two adjacent qubits without having to isolate the two qubits from qubits adjacent to them. The gate operation is implemented by applying two consecutive pulses of equal duration, but varying amplitudes, on the target qubit. Since only a single control parameter is required in implementing our scheme, it is very efficient. We next show how our scheme can be used to realize single qubit rotations and two-qubit controlled-unitary operations. As most proposals for solid state implementations of a quantum computer use a one-dimensional line of qubits, the schemes presented here will be extremely useful.

scholarly journals Encoding Two-Qubit Logical States and Quantum Operations Using the Energy States of a Physical System

Technologies ◽  
2021 ◽  
Vol 10 (1) ◽  
pp. 1
Author(s):  
Dimitrios Ntalaperas ◽  
Nikos Konofaos
Keyword(s):  
Quantum Computer ◽  
Quantum Systems ◽  
Quantum States ◽  
Discrete Energy ◽  
Quantum Operations ◽  
Single Qubit ◽  
Use Of Resources ◽  
Energy States ◽  
Qubit Operations ◽  
Charge Degree

In this paper, we introduce a novel coding scheme, which allows single quantum systems to encode multi-qubit registers. This allows for more efficient use of resources and the economy in designing quantum systems. The scheme is based on the notion of encoding logical quantum states using the charge degree of freedom of the discrete energy spectrum that is formed by introducing impurities in a semiconductor material. We propose a mechanism of performing single qubit operations and controlled two-qubit operations, providing a mechanism for achieving these operations using appropriate pulses generated by Rabi oscillations. The above architecture is simulated using the Armonk single qubit quantum computer of IBM to encode two logical quantum states into the energy states of Armonk’s qubit and using custom pulses to perform one and two-qubit quantum operations.

Single-qubit operations on the Kane quantum computer

2002 ◽  
Vol 13 (5) ◽  
pp. 570-575 ◽  
Author(s):  
C J Wellard ◽  
L C L Hollenberg ◽  
C I Pakes
Keyword(s):  
Quantum Computer ◽  
Single Qubit ◽  
Qubit Operations

Dynamics of nuclear spin measurement in a mesoscopic solid-state quantum computer

2000 ◽  
Vol 12 (13) ◽  
pp. 2945-2952 ◽  
Author(s):  
Gennady P Berman ◽  
David K Campbell ◽  
Gary D Doolen ◽  
Kirill E Nagaev
Keyword(s):  
Solid State ◽  
Nuclear Spin ◽  
Quantum Computer

scholarly journals Spin diffusion and relaxation in solid state spin quantum computer

2006 ◽  
Vol 352 (1-2) ◽  
pp. 107-114
Author(s):  
G.P. Berman ◽  
B.M. Chernobrod ◽  
V.N. Gorshkov ◽  
V.I. Tsifrinovich
Keyword(s):  
Solid State ◽  
Spin Diffusion ◽  
Quantum Computer ◽  
Spin Quantum ◽  
State Spin

scholarly journals Two-dimensional semiconductors pave the way towards dopant-based quantum computing

2018 ◽  
Vol 9 ◽  
pp. 2668-2673 ◽  
Author(s):  
José Carlos Abadillo-Uriel ◽  
Belita Koiller ◽  
María José Calderón
Keyword(s):  
Conduction Band ◽  
Quantum Computer ◽  
2D Materials ◽  
Exchange Interactions ◽  
Lattice Parameter ◽  
Oscillatory Behavior ◽  
Conduction Band Edge ◽  
Two Dimensional ◽  
Tunnel Coupling ◽  
Qubit Operations

Since the proposal in 1998 to build a quantum computer using dopants in silicon as qubits, much progress has been made in the nanofabrication of semiconductors and the control of charge and spins in single dopants. However, an important problem remains unsolved, namely the control over exchange interactions and tunneling between two donors, which presents a peculiar oscillatory behavior as the dopants relative positions vary at the scale of the lattice parameter. Such behavior is due to the valley degeneracy in the conduction band of silicon, and does not occur when the conduction-band edge is at k = 0. We investigate the possibility of circumventing this problem by using two-dimensional (2D) materials as hosts. Dopants in 2D systems are more tightly bound and potentially easier to position and manipulate. Moreover, many of them present the conduction band minimum at k = 0, thus no exchange or tunnel coupling oscillations. Considering the properties of currently available 2D semiconductor materials, we access the feasibility of such a proposal in terms of quantum manipulability of isolated dopants (for single qubit operations) and dopant pairs (for two-qubit operations). Our results indicate that a wide variety of 2D materials may perform at least as well as, and possibly better, than the currently studied bulk host materials for donor qubits.

scholarly journals A silicon-based surface code quantum computer

2016 ◽  
Vol 2 (1) ◽  
Author(s):  
Joe O’Gorman ◽  
Naomi H Nickerson ◽  
Philipp Ross ◽  
John JL Morton ◽  
Simon C Benjamin
Keyword(s):  
Quantum Computing ◽  
Solid State ◽  
Quantum Computer ◽  
Fault Tolerant ◽  
Device Fabrication ◽  
Impurity Atoms ◽  
Dipole Interactions ◽  
Total Phase ◽  
Surface Code ◽  
Silicon Based

Abstract Individual impurity atoms in silicon can make superb individual qubits, but it remains an immense challenge to build a multi-qubit processor: there is a basic conflict between nanometre separation desired for qubit–qubit interactions and the much larger scales that would enable control and addressing in a manufacturable and fault-tolerant architecture. Here we resolve this conflict by establishing the feasibility of surface code quantum computing using solid-state spins, or ‘data qubits’, that are widely separated from one another. We use a second set of ‘probe’ spins that are mechanically separate from the data qubits and move in and out of their proximity. The spin dipole–dipole interactions give rise to phase shifts; measuring a probe’s total phase reveals the collective parity of the data qubits along the probe’s path. Using a protocol that balances the systematic errors due to imperfect device fabrication, our detailed simulations show that substantial misalignments can be handled within fault-tolerant operations. We conclude that this simple ‘orbital probe’ architecture overcomes many of the difficulties facing solid-state quantum computing, while minimising the complexity and offering qubit densities that are several orders of magnitude greater than other systems.

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