Supercomputing with spin-polarized single electrons in a quantum coupled architecture

Bandyopadhyay, Supriyo; Das, Bipul; Miller, A. E.

doi:10.1088/0957-4484/5/2/007

Cited by 119 publications

(80 citation statements)

References 76 publications

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“…There is great interest at this time in the possibility of low-power switching through spin-based systems 4,6,7,8 . However, a simple scheme employing a z directed magnetic field to switch 'up' (+z) spins to 'down' (-z) will also require a minimum dissipation of N kT lnr.…”

Section: Pacs Numbersmentioning

confidence: 99%

Interacting systems for self-correcting low power switching

Salahuddin¹,

Datta²

2007

Applied Physics Letters

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In this paper we first show that dynamic switching schemes can be used to reduce energy dissipation below the thermodynamic minimum of N kT lnr (N = number of state variables, 1/r=error probability), but only at the expense of the error immunity inherent in thermodynamic processes for which the final state is insensitive to the switching dynamics. It is further shown that, for a system which has internal feedback, e.g. nanomagnets, such that all N spins act in concert, it should be possible to switch with an energy dissipation of the order of kT lnr (considerably less than the thermodynamic limit of N kT lnr), while retaining an error immunity comparable to thermodynamic switching.

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Section: Pacs Numbersmentioning

confidence: 99%

Interacting systems for self-correcting low power switching

Salahuddin¹,

Datta²

2007

Applied Physics Letters

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“…For example, chains of coupled adatoms, which communicate the spin state through RKKY interaction, can serve to build elements for spinlogic circuits carrying out conventional binary computation using only the spin degree of freedom 27 . Finally, we anticipate that the demonstrated methods for extracting the interactions between individual magnetic atoms can be applied to other systems where a detailed knowledge of the indirect exchange is still lacking.…”

mentioning

confidence: 99%

Strength and directionality of surface Ruderman–Kittel–Kasuya–Yosida interaction mapped on the atomic scale

et al. 2010

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Ruderman-Kittel-Kasuya-Yosida interaction [1][2][3] is an indirect magnetic coupling between localized spins in a non-magnetic host mediated by conduction electrons. In diluted systems it is often the dominating magnetic interaction and has played a key part in the development of giant magnetoresistance devices 4,5 , drives ferromagnetism in heavy rare-earth elements 6 as well as in diluted magnetic semiconductors 7 and gives rise to complex magnetic phases such as spin glasses 8 . For bulk systems, an isotropic and continuous model of Ruderman-Kittel-KasuyaYosida interaction is often sufficient. However, it can be misleading in magnetic nanostructures consisting of separate magnetic atoms adsorbed on the surface of a non-magnetic material. Here, an atomically precise map of the magnetic coupling between individual adatoms in pairs is measured and directly compared with first-principles calculations, proving that Ruderman-Kittel-Kasuya-Yosida interaction is strongly directional. By investigating adatom triplets of different shapes we demonstrate that the map can serve to tailor the magnetism of larger nanostructures.Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction is ubiquitous in solid-state systems containing diluted magnetic moments in a conducting non-magnetic host. It becomes dominant whenever there is a sufficiently strong exchange coupling between the localized moments and the conduction electrons. Then, the spins of the conduction electrons, which are on average unpolarized, are forced into a preferred direction in the vicinity of each moment. This preferential direction oscillates with increasing distance from the moment. A second localized moment will interact with this spin-density oscillation and perceive either a ferromagnetic or an antiferromagnetic coupling to the first, depending on their distance. Therefore, RKKY interaction is also called indirect magnetic exchange. The first indications of indirect magnetic exchange through conduction electrons came with the research on diluted bulk alloys, where a dependence of the interaction strength on the distance between the moments with an oscillation period of half the Fermi wavelength was proposed in an isotropic and continuous model [1][2][3] . Direct experimental evidence for RKKY-like coupling of magnetic layers through transition-metal layers was obtained by spatial-averaging techniques [9][10][11][12] . There have been theoretical [13][14][15] and experimental 16 hints that accurate RKKY models have to take into account the topology of the Fermi surface and the discrete distribution of magnetic moments on the atomic lattice, but a direct experimental proof was hampered by the spatial averaging, which provides only fragmentary information on the distribution. However, as magnetic devices are becoming smaller and approaching the limit of nanostructures built by separate atoms, knowledge of the RKKY interaction on the atomic scale is essential.By using scanning tunnelling spectroscopy, it became possible to investigate magnetic interactions in atom ...

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“…The notion of using the bistable spin polarizations of a single electron placed in a magnetic field to encode the binary bits 0 and 1 is at the heart of an exotic idea known as Single Spin Logic (SSL) [3][4][5][6][7][8].…”

Section: Single Spin Logic (Ssl)mentioning

confidence: 99%

Information Processing with Electron Spins

Bandyopadhyay

2012

ISRN Materials Science

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Information processors process information in a variety of ways. The human brain processes information through a highly interconnected system of neurons and synapses, while a digital computer processes information by having a binary switch toggle on and off in response to a stream of binary bits. The "switch" is the most primitive unit of the modern computer. The better it is (faster, more energy efficient, more reliable, etc.), the more advanced is the computer hardware. Energy efficiency, however, is more important than any other attribute, not so much because energy is costly, but because too much energy dissipation prevents increasing the density of switches on a chip that is necessary to make the chip increasingly more powerful. Reducing dissipation entails radically new and often revolutionary approaches for implementing the switch. One such approach is to encode digital bit information in the spin polarization of a single electron (or ensemble of electrons) and then using two mutually antiparallel polarizations to represent the binary bits 0 and 1. Switching between the bits can be accomplished by simply flipping the polarizations of the spins, which takes very little energy. Such switches are extremely energy efficient if designed properly, but they are somewhat slower than traditional transistor-based switches and can be more error prone. This paper discusses the pros and cons of spin-based switches and introduces the reader to the most recent advancements in information processing predicated on encoding information in electron spin polarization.

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Supercomputing with spin-polarized single electrons in a quantum coupled architecture

Cited by 119 publications

References 76 publications

Interacting systems for self-correcting low power switching

Interacting systems for self-correcting low power switching

Strength and directionality of surface Ruderman–Kittel–Kasuya–Yosida interaction mapped on the atomic scale

Information Processing with Electron Spins

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