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

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.

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 Silicon-based spin and charge quantum computation

2005 ◽  
Vol 77 (2) ◽  
pp. 201-222 ◽  
Author(s):  
Belita Koiller ◽  
Xuedong Hu ◽  
Rodrigo B. Capaz ◽  
Adriano S. Martins ◽  
Sankar Das Sarma
Keyword(s):  
Quantum Computation ◽  
Quantum Interference ◽  
Quantum Computer ◽  
Building Blocks ◽  
Shallow Donor ◽  
Molecular Ions ◽  
Conduction Band Edge ◽  
Tunnel Coupling ◽  
Qubit Operations ◽  
Silicon Based

Silicon-based quantum-computer architectures have attracted attention because of their promise for scalability and their potential for synergetically utilizing the available resources associated with the existing Si technology infrastructure. Electronic and nuclear spins of shallow donors (e.g. phosphorus) in Si are ideal candidates for qubits in such proposals due to the relatively long spin coherence times. For these spin qubits, donor electron charge manipulation by external gates is a key ingredient for control and read-out of single-qubit operations, while shallow donor exchange gates are frequently invoked to perform two-qubit operations. More recently, charge qubits based on tunnel coupling in P+2 substitutional molecular ions in Si have also been proposed. We discuss the feasibility of the building blocks involved in shallow donor quantum computation in silicon, taking into account the peculiarities of silicon electronic structure, in particular the six degenerate states at the conduction band edge. We show that quantum interference among these states does not significantly affect operations involving a single donor, but leads to fast oscillations in electron exchange coupling and on tunnel-coupling strength when the donor pair relative position is changed on a lattice-parameter scale. These studies illustrate the considerable potential as well as the tremendous challenges posed by donor spin and charge as candidates for qubits in silicon.

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 Benchmarking an 11-qubit quantum computer

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
K. Wright ◽  
K. M. Beck ◽  
S. Debnath ◽  
J. M. Amini ◽  
Y. Nam ◽  
...  
Keyword(s):  
Quantum Computing ◽  
Quantum Physics ◽  
Quantum Computer ◽  
Success Rates ◽  
Single Qubit ◽  
The Past ◽  
Large Numbers ◽  
Universal Quantum ◽  
Qubit Gate ◽  
Fully Connected

AbstractThe field of quantum computing has grown from concept to demonstration devices over the past 20 years. Universal quantum computing offers efficiency in approaching problems of scientific and commercial interest, such as factoring large numbers, searching databases, simulating intractable models from quantum physics, and optimizing complex cost functions. Here, we present an 11-qubit fully-connected, programmable quantum computer in a trapped ion system composed of 13 171Yb+ ions. We demonstrate average single-qubit gate fidelities of 99.5$$\%$$%, average two-qubit-gate fidelities of 97.5$$\%$$%, and SPAM errors of 0.7$$\%$$%. To illustrate the capabilities of this universal platform and provide a basis for comparison with similarly-sized devices, we compile the Bernstein-Vazirani and Hidden Shift algorithms into our native gates and execute them on the hardware with average success rates of 78$$\%$$% and 35$$\%$$%, respectively. These algorithms serve as excellent benchmarks for any type of quantum hardware, and show that our system outperforms all other currently available hardware.

scholarly journals APPLICATIONS OF ATOMIC ENSEMBLES IN DISTRIBUTED QUANTUM COMPUTING

2010 ◽  
Vol 08 (01n02) ◽  
pp. 181-218 ◽  
Author(s):  
MARCIN ZWIERZ ◽  
PIETER KOK
Keyword(s):  
Quantum Information ◽  
Quantum Computation ◽  
Quantum Computer ◽  
Success Probability ◽  
Quantum Memory ◽  
Quantum Network ◽  
Atomic Ensembles ◽  
Cluster States ◽  
Ghz States ◽  
Single Qubit

Thesis chapter. The fragility of quantum information is a fundamental constraint faced by anyone trying to build a quantum computer. A truly useful and powerful quantum computer has to be a robust and scalable machine. In the case of many qubits which may interact with the environment and their neighbors, protection against decoherence becomes quite a challenging task. The scalability and decoherence issues are the main difficulties addressed by the distributed model of quantum computation. A distributed quantum computer consists of a large quantum network of distant nodes — stationary qubits which communicate via flying qubits. Quantum information can be transferred, stored, processed and retrieved in decoherence-free fashion by nodes of a quantum network realized by an atomic medium — an atomic quantum memory. Atomic quantum memories have been developed and demonstrated experimentally in recent years. With the help of linear optics and laser pulses, one is able to manipulate quantum information stored inside an atomic quantum memory by means of electromagnetically induced transparency and associated propagation phenomena. Any quantum computation or communication necessarily involves entanglement. Therefore, one must be able to entangle distant nodes of a distributed network. In this article, we focus on the probabilistic entanglement generation procedures such as well-known DLCZ protocol. We also demonstrate theoretically a scheme based on atomic ensembles and the dipole blockade mechanism for generation of inherently distributed quantum states so-called cluster states. In the protocol, atomic ensembles serve as single qubit systems. Hence, we review single-qubit operations on qubit defined as collective states of atomic ensemble. Our entangling protocol requires nearly identical single-photon sources, one ultra-cold ensemble per physical qubit, and regular photodetectors. The general entangling procedure is presented, as well as a procedure that generates in a single stepQ-qubit GHZ states with success probability psuccess ~ ηQ/2, where η is the combined detection and source efficiency. This is significantly more efficient than any known robust probabilistic entangling operation. The GHZ states form the basic building block for universal cluster states, a resource for the one-way quantum computer.

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