# Faster than allowed by quantum computing?

February 01, 2019Computers are an integral part of our daily lives. What has once been science fiction is now real technology in our pockets. But computers are physical objects. And as quantum computation has taught us, new insights into physics can sometimes lead to new types of computers.

What kinds of computers would be conceivable if physics worked differently? The quantum physicists Marius Krumm from the University of Vienna and Markus Müller from the Viennese Institute of Quantum Optics and Quantum Information of the Austrian Academy of Sciences (ÖAW) have addressed this question. Theoretical properties of such "science fiction computers" could give us interesting insights into quantum computing.

**Bits and Qubits**

The key elements of classical and quantum computers are the bits: alternatives of "yes" and "no", wired together in a circuit. On an ordinary laptop, these bits would have to be either 0 or 1. Quantum computers, on the other hand, work with quantum bits: we can think of these as points on a three-dimensional ball. The north pole represents 0 and the south pole 1. A "qubit" can also take any place in between (for example on the equator) - the so-called superposition states.

In their current study, Krumm and Müller consider bits as points on a ball, too. But in contrast to the quantum bit, this ball does not need to be three-dimensional. A few years ago, two quantum physicists from the University of Vienna and the Austrian Academy of Sciences, Borivoje Daki? and ?aslav Brukner, have conjectured that these balls describe alternative physics in worlds with more than three spatial dimensions. To check this idea, Krumm and Müller have made two assumptions on how these bits are wired: first, they are processed via reversible gates, like "AND" or "NOT". Second, they satisfy an intuitive property of classical and quantum computing: knowing the single bits and how they are correlated tells us everything there is to know.

The surprising result: even though their bits would be more complicated, these computers would have extremely limited capabilities. They would not be faster than quantum computers and could not even execute ordinary algorithms. In this sense, dimension three and the quantum bit are special, and so is quantum computation: in a phrase coined previously by computer scientist Scott Aaronson, it is an "island in theoryspace".

-end-

Publication in *Nature Quantum Information*:

Marius Krumm & Markus P. Müller: Quantum computation is the unique reversible circuit model for which bits are balls (2019)

DOI: 10.1038/s41534-018-0123-x

University of Vienna

## Related Quantum Computing Articles from Brightsurf:

Bringing a power tool from math into quantum computing

The Fourier transform is a mathematical operation essential to virtually all fields of physics and engineering.

New detector breakthrough pushes boundaries of quantum computing

A new paper published in Nature shows potential for graphene bolometers to become a game-changer for quantum technology

A molecular approach to quantum computing

Molecules in quantum superposition could help in the development of quantum computers.

Cosmic rays may soon stymie quantum computing

Infinitesimally low levels of radiation, such as from incoming cosmic rays, may soon stymie progress in quantum computing.

UVA pioneers study of genetic diseases with quantum computing

Scientists are harnessing the mind-bending potential of quantum computers to help us understand genetic diseases - even before quantum computers are a thing.

New method predicts spin dynamics of materials for quantum computing

Researchers at UC Santa Cruz have developed a theoretical foundation and new computational tools for predicting a material's spin dynamics, a key property for building solid-state quantum computing platforms and other applications of spintronics.

Speeding-up quantum computing using giant atomic ions

An international team of researchers have found a new way to speed up quantum computing that could pave the way for huge leaps forward in computer processing power.

Boson particles discovery provides insights for quantum computing

Researchers working on a U.S. Army project discovered a key insight for the development of quantum devices and quantum computers.

In leap for quantum computing, silicon quantum bits establish a long-distance relationship

In an important step forward in the quest to build a quantum computer using silicon-based hardware, researchers at Princeton have succeeded in making possible the exchange of information between two qubits located relatively far apart -- about the length of a grain of rice, which is a considerable distance on a computer chip.

Diversity may be key to reducing errors in quantum computing

In quantum computing, as in team building, a little diversity can help get the job done better, computer scientists have discovered.

Read More: Quantum Computing News and Quantum Computing Current Events

The Fourier transform is a mathematical operation essential to virtually all fields of physics and engineering.

New detector breakthrough pushes boundaries of quantum computing

A new paper published in Nature shows potential for graphene bolometers to become a game-changer for quantum technology

A molecular approach to quantum computing

Molecules in quantum superposition could help in the development of quantum computers.

Cosmic rays may soon stymie quantum computing

Infinitesimally low levels of radiation, such as from incoming cosmic rays, may soon stymie progress in quantum computing.

UVA pioneers study of genetic diseases with quantum computing

Scientists are harnessing the mind-bending potential of quantum computers to help us understand genetic diseases - even before quantum computers are a thing.

New method predicts spin dynamics of materials for quantum computing

Researchers at UC Santa Cruz have developed a theoretical foundation and new computational tools for predicting a material's spin dynamics, a key property for building solid-state quantum computing platforms and other applications of spintronics.

Speeding-up quantum computing using giant atomic ions

An international team of researchers have found a new way to speed up quantum computing that could pave the way for huge leaps forward in computer processing power.

Boson particles discovery provides insights for quantum computing

Researchers working on a U.S. Army project discovered a key insight for the development of quantum devices and quantum computers.

In leap for quantum computing, silicon quantum bits establish a long-distance relationship

In an important step forward in the quest to build a quantum computer using silicon-based hardware, researchers at Princeton have succeeded in making possible the exchange of information between two qubits located relatively far apart -- about the length of a grain of rice, which is a considerable distance on a computer chip.

Diversity may be key to reducing errors in quantum computing

In quantum computing, as in team building, a little diversity can help get the job done better, computer scientists have discovered.

Read More: Quantum Computing News and Quantum Computing Current Events

Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.