Quantum Entanglement Of Three Electrons Achieved

The quantum entanglement of three electrons, using an ultrafast optical pulse and a quantum well of a magnetic semiconductor material, has been demonstrated in a laboratory at the University of Michigan, marking another step toward the realization of a practical quantum computer. While several experiments in recent years have succeeded in entangling pairs of particles, few researchers have managed to correlate three or more particles in a predictable fashion.

The results were presented in an article on Nature Materials’ web site on February 23 and will appear in the March 4 issue of Nature Materials, titled “Optically induced multispin entanglement in a semiconductor quantum well.” Authors of the paper are Jiming Bao, Andrea V. Bragas, Jacek K. Furdyna (University of Notre Dame), and Roberto Merlin.

Entanglement, which is essential to the creation of a quantum computer, is one of the mysterious properties of quantum mechanics that contradicts the notions of classical realism. Quantum computers will be able to perform highly complex tasks that would be impossible for a classical computer, at great speed.

Briefly, entanglement describes a particular state of a set of particles of energy or matter for which correlations exist, so that the particles affect each other regardless of how far apart they are. Einstein called it “spooky action at a distance.” We know that we must be able to harness entanglement in order to develop the quantum gates necessary for storing and processing information in practical quantum computers. These devices will offer enormously enhanced computing power that would permit extremely fast ways to solve certain mathematical problems, such as the factorization of large numbers.

The Michigan team, which has been working on the problem for several years, used ultrafast (50-100 femtosecond) laser pulses and coherent techniques to create and control spin-entangled states in a set of non-interacting electrons bound to donors in a CdTe quantum well. The method, which relies on the exchange interaction between localized excitons and paramagnetic impurities, could in principle be used to entangle an arbitrarily large number of spins.

In the presence of an external magnetic field, a resonant laser pulse creates localized excitons (bound electron-hole pairs) of radius ~ 0.005 microns in the CdTe well. Electrons bound to donor impurities within that radius feel the presence of the exciton in such a way that they became entangled after the exciton is gone. The process involves resonant Raman transitions between Zeeman split spin states. In the experiments, the signature of entanglement involving m electrons is the detection of the mth-harmonic of the fundamental Zeeman frequency in the differential reflectivity data.

“The community is trying various approaches to achieve controllable interactions between qubits. We’ve seen a variety of proposed solutions from atomic physicists involving trapped ions and atoms and even ‘flying qubits’ based on light,” said Merlin. “Solutions based on semiconductor technology, like ours for example, may well hold more promise for practical implementation when combined with advances in nanotechnology.”

The experiments have so far involved a large ensemble of sets of 3 electrons. “Our procedure is potentially set-specific and scalable, which means that it shows definite promise for quantum computing applications,” Merlin said. Cryptography is expected to be one of the first such applications.

Comments are closed.

Johnson Controls Metasys Field Equipment Controller MS-FAC4911-0 FAC FAC4911 picture

Johnson Controls Metasys Field Equipment Controller MS-FAC4911-0 FAC FAC4911

$600.00



Johnson Controls M4-CVM03050-0 Metasys CVM03050 Vav Box Controller picture

Johnson Controls M4-CVM03050-0 Metasys CVM03050 Vav Box Controller

$399.00



Johnson Controls Metasys Software picture

Johnson Controls Metasys Software

$80.00



Johnson Controls Metasys IOM4711 Expansion Module MS-IOM4711-0  picture

Johnson Controls Metasys IOM4711 Expansion Module MS-IOM4711-0

$99.99



Metasys Johnson Controls (lot of 10)  AP-VMA1420-0 coupling/bushing AP-VMA1410-0 picture

Metasys Johnson Controls (lot of 10)  AP-VMA1420-0 coupling/bushing AP-VMA1410-0

$50.00



Johnson Controls Metasys AS-UNT1144-0 Unitary Controller  (New in Box) picture

Johnson Controls Metasys AS-UNT1144-0 Unitary Controller (New in Box)

$499.00



Johnson Controls AP-VMA1420-0 Metasys Variable Air Volume Modular Assembly 24vac picture

Johnson Controls AP-VMA1420-0 Metasys Variable Air Volume Modular Assembly 24vac

$50.00



Johnson Controls FEC2611 Metasys System Field Equipment Controller picture

Johnson Controls FEC2611 Metasys System Field Equipment Controller

$99.99



Johnson Controls MS-ZFR1811-1 Metasys Line Wireless Flag picture

Johnson Controls MS-ZFR1811-1 Metasys Line Wireless Flag

$25.00



Johnson Controls DX9100 Expansion Module MetaSys 4DI4DO XP-9104-8304 picture

Johnson Controls DX9100 Expansion Module MetaSys 4DI4DO XP-9104-8304

$34.99



Powered by WordPress. Designed by WooThemes