scholarly journals Quantum networks: topology and spectral characterization

2018 ◽  
Vol 182 ◽  
pp. 02014
Author(s):  
Vesna Berec
Keyword(s):  
Quantum Information Processing ◽  
Theoretic Approach ◽  
Quantum State Transfer ◽  
Complexity Measures ◽  
Quantum Networks ◽  
Graph Theoretic ◽  
Topological Features ◽  
State Transfer ◽  
Quantum Complexity ◽  
And Control

To utilize a scalable quantum network and perform a quantum state transfer within distant arbitrary nodes, coherence and control of the dynamics of couplings between the information units must be achieved as a prerequisite ingredient for quantum information processing within a hierarchical structure. Graph theoretic approach provides a powerful tool for the characterization of quantum networks with non-trivial clustering properties. By encoding the topological features of the underlying quantum graphs, relations between the quantum complexity measures are presented revealing the intricate links between a quantum and a classical networks dynamics.

scholarly journals Dual-species, multi-qubit logic primitives for Ca+/Sr+ trapped-ion crystals

2019 ◽  
Vol 5 (1) ◽  
Author(s):  
C. D. Bruzewicz ◽  
R. McConnell ◽  
J. Stuart ◽  
J. M. Sage ◽  
J. Chiaverini
Keyword(s):  
Quantum Logic ◽  
Near Infrared ◽  
Quantum Information Processing ◽  
Infrared Range ◽  
Sympathetic Cooling ◽  
Trapped Ion ◽  
Logic Control ◽  
State Transfer ◽  
And Control ◽  
Near Infrared Range

AbstractWe demonstrate key multi-qubit quantum-logic primitives in a dual-species trapped-ion system based on $${}^{40}$$40Ca$${}^{+}$$+ and $${}^{88}$$88Sr$${}^{+}$$+ ions, using two optical qubits with quantum-logic-control frequencies in the red to near-infrared range. With all ionization, cooling, and control wavelengths in a wavelength band similar for the two species and centered in the visible, and with a favorable mass ratio for sympathetic cooling, this pair is a promising candidate for scalable quantum information processing. Same-species and dual-species two-qubit gates, based on the Mølmer–Sørensen interaction and performed in a cryogenic surface-electrode trap, are characterized via the fidelity of generated entangled states; we achieve fidelities of 98.8(2)% and 97.5(2)% in Ca$${}^{+}$$+–Ca$${}^{+}$$+ and Sr$${}^{+}$$+–Sr$${}^{+}$$+ gates, respectively. For a similar Ca$${}^{+}$$+–Sr$${}^{+}$$+ gate, we achieve a fidelity of 94.3(3)%, and carrying out a Sr$${}^{+}$$+–Sr$${}^{+}$$+ gate performed with a Ca$${}^{+}$$+ sympathetic cooling ion in a Sr$${}^{+}$$+–Ca$${}^{+}$$+–Sr$${}^{+}$$+ crystal configuration, we achieve a fidelity of 95.7(3)%. These primitives form a set of trapped-ion capabilities for logic with sympathetic cooling and ancilla readout or state transfer for general quantum computing and communication applications.

QUANTUM INFORMATION PROCESSING IN AN ARRAY OF SUPERCONDUCTING TRANSMISSION LINE RESONATORS

2009 ◽  
Vol 07 (06) ◽  
pp. 1255-1267
Author(s):  
JIAN LI ◽  
JIAN ZOU ◽  
BIN SHAO
Keyword(s):  
Information Processing ◽  
Quantum Information ◽  
Transmission Line ◽  
Quantum State ◽  
Quantum Information Processing ◽  
Quantum State Transfer ◽  
Superconducting Qubit ◽  
One Dimensional ◽  
Dimensional Array ◽  
State Transfer

We consider a one-dimensional array of superconducting transmission line resonators (TLRs). The TLRs are coupled by current-biased Josephson junctions, which act as tunable couplers between each two nearest TLRs, and a superconducting qubit is fabricated in the center of each TLR. We show that some important quantum information processing, such as quantum state transfer and preparation of remote entanglement, can be achieved in this system, and we also propose a scheme for generating the W-class states.

scholarly journals QUANTUM STATE TRANSFER THROUGH A QUBIT NETWORK WITH ENERGY SHIFTS AND FLUCTUATIONS

2009 ◽  
Vol 07 (08) ◽  
pp. 1417-1427 ◽  
Author(s):  
ANDREA CASACCINO ◽  
SETH LLOYD ◽  
STEFANO MANCINI ◽  
SIMONE SEVERINI
Keyword(s):  
Quantum State ◽  
Quantum State Transfer ◽  
Quantum Networks ◽  
Missing Link ◽  
Analytical Results ◽  
State Transfer ◽  
Perfect Transfer ◽  
Random Fluctuations

We study quantum state transfer through a qubit network modeled by spins with XY interaction, when relying on a single excitation. We show that it is possible to achieve perfect transfer by shifting (adding) energy to specific vertices. This technique appears to be a potentially powerful tool for changing, and in some cases improving, the transfer capabilities of quantum networks. Analytical results are presented for all-to-all networks and for all-to-all networks with a missing link. Moreover, we evaluate the effect of random fluctuations on the transmission fidelity.

scholarly journals Quantum information processing with quantum zeno many-body dynamics

2010 ◽  
Vol 10 (3&4) ◽  
pp. 201-222
Author(s):  
A. Monras ◽  
O. Romero-Isart
Keyword(s):  
Quantum Information ◽  
Quantum Information Processing ◽  
Quantum Zeno Effect ◽  
Quantum State Transfer ◽  
Many Body ◽  
One Dimensional ◽  
Zeno Effect ◽  
State Transfer ◽  
Body Dynamics ◽  
Universal Quantum

We show how the quantum Zeno effect can be exploited to control quantum many-body dynamics for quantum information and computation purposes. In particular, we consider a one dimensional array of three level systems interacting via a nearest-neighbour interaction. By encoding the qubit on two levels and using simple projective frequent measurements yielding the quantum Zeno effect, we demonstrate how to implement a well defined quantum register, quantum state transfer on demand, universal two-qubit gates and two-qubit parity measurements. Thus, we argue that the main ingredients for universal quantum computation can be achieved in a spin chain with an {\em always-on} and {\em constant} many-body Hamiltonian. We also show some possible modifications of the initially assumed dynamics in order to create maximally entangled qubit pairs and single qubit gates.

scholarly journals Electrical control of strong spin-phonon coupling in a carbon nanotube

2017 ◽  
Vol 17 (1&2) ◽  
pp. 117-124
Author(s):  
Fang-Yu Hong ◽  
Jing-Li Fu ◽  
Yan Wu ◽  
Zhi-Yan Zhu
Keyword(s):  
Carbon Nanotube ◽  
Quantum Dot ◽  
Quantum Information Processing ◽  
Phonon Coupling ◽  
Quantum State Transfer ◽  
Spin Qubits ◽  
Electrical Control ◽  
State Transfer ◽  
Electrical Pulses ◽  
Effective Center

We describe an approach to electrically control the strong interaction between a single electron spin and the vibrational motion of a suspended carbon nanotube resonator. The strength of the deflection-induced spin-phonon coupling is dependent on the wavefunction of the electron confined in a lateral carbon nanotube quantum dot. An electrical field along the nanotube shifts the effective center of the quantum dot, leading to the corresponding modification of the spin-phonon strength. Numerical simulations with experimentally reachable parameters show that high fidelity quantum state transfer between mechanical and spin qubits driven by electrical pulses is feasible. Our results form the basis for the fully electrical control of the coherent interconvertion between light and spin qubits and for manufacturing electrically driven quantum information processing systems.

ENTANGLEMENT PREPARATION AND QUANTUM INFORMATION PROCESSING WITH ATOMS TRAPPED IN SEPARATED CAVITIES THROUGH A SINGLE RESONANT ATOM–FIELD INTERACTION

2014 ◽  
Vol 28 (02) ◽  
pp. 1450015
Author(s):  
LI-HUA LIN
Keyword(s):  
Optical Fibers ◽  
Quantum Information Processing ◽  
Classical Field ◽  
Single Atom ◽  
Quantum Network ◽  
Quantum State Transfer ◽  
Field Interaction ◽  
State Transfer ◽  
Resonant Atom ◽  
Fiber Interaction

In this paper, a scheme is presented for generation of W-type entangled states for n atoms trapped in separated cavities connected by optical fibers. The scheme only requires a single atom–cavity–fiber interaction and no classical field is needed. Due to these features, the scheme is simpler and more robust against decoherence than the previous ones. The scheme can also be used to realize quantum state transfer and controlled phase gates between qubits located at distant nodes of a quantum network.

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