Carbon nanotube computer

A carbon nanotube computer is a computer built entirely using carbon nanotubes (CNT) based transistors.[1][2]

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Researchers from Stanford University said that they had successfully built a carbon nanotube computer and their research paper published on 25 September 2013 in the journal Nature.[3] They named their first carbon nanotube computer Cedric.[4] It has a one-bit processor containing just 178 transistors.[5]

In 2019, a team at the Massachusetts Institute of Technology created the 16-bit processor called RV16X-NANO. With 14,000 transistors (compared to only hundreds in the first CNT computer made in 2013) it is the largest computer chip yet to be made from carbon nanotubes. It was able to execute a "Hello, World!" program with a message: “Hello, world! I am RV16XNano, made from CNTs”.[6] It is based on the RISC-V instruction set and runs standard 32-bit instructions on 16-bit data and addresses.[7][8]

Cedric

Features

The only operation that Cedric can carry out is the SUBNEG instruction, which is short for "Subtract and branch if negative". This is a very simple instruction and can still be used to achieve Turing completeness. With SUBNEG, Cedric can count, order numbers and choose between two values. Due to the fact that Cedric only has a single instruction in its architecture, it is classified as an One instruction set computer (OISC).

Current miniaturization and theoretical limits

Cedric has a miniaturization level of 8,000 nanometers, while the theoretical limit is 24—32 nanometers.

Practical problems of realization

The biggest problem in building a carbon nanotube computer in general is the alignment of the carbon nanotubes. This is what Shulaker said about it:

"We had to do a lot of work to get these nanotubes to align how we wanted, and to be perfectly reliable.

We had to do a lot of work to get these nanotubes aligned as we wanted, and to do it in a perfectly reliable way "

Even 98% accuracy is not acceptable, because out of one billion transistors this means 20,000,000 (20 million) non-functioning transistors which effectively block the computer from functioning. This issue was solved with a system that uses electricity to vaporize the misaligned nanotubes. However, thanks to an algorithm, a working computer is obtained even if not all the nanotubes are aligned. This approach is extremely important because it is industrially usable, in fact making it possible to mass-produce carbon nanotube computers.[9] Cedric has 0.5% of non-aligned nanotubes but thanks to this algorithm it works anyway.

Benefits
  • Transistor-based digital circuits fabricated from carbon nanotubes can potentially outperform silicon by more than an order of magnitude.

Probable date of marketing

It is realistic that carbon nanotube computers will be commercialized between 2023 and 2025.[10]

References
  1. Shulaker, Max M.; Hills, Gage; Patil, Nishant; Wei, Hai; Chen, Hong-Yu; Wong, H.-S. Philip; Mitra, Subhasish (25 September 2013). "Carbon nanotube computer". Nature. 501 (7468): 526–530. Bibcode:2013Natur.501..526S. doi:10.1038/nature12502. PMID 24067711. S2CID 205235321.
  2. "First computer made of carbon nanotubes is unveiled". BBC. 26 September 2013. Retrieved 26 September 2013.
  3. "Researchers Build a Working Carbon Nanotube Computer". NY Times. 26 September 2013. Retrieved 26 September 2013.
  4. "Scientists create first carbon nanotube computer". Washingtonpost. 26 September 2013. Retrieved 26 September 2013.
  5. "First Computer Made From Carbon Nanotubes Debuts". IEEE Spectrum: Technology, Engineering, and Science News. Retrieved 19 September 2019.
  6. Gibney, Elizabeth (28 August 2019). "Biggest carbon-nanotube chip yet says 'Hello, World!'". Nature. doi:10.1038/d41586-019-02576-7. PMID 32848234.
  7. Shulaker, Max M.; Chandrakasan, Anantha; Murphy, Denis; Stein, Yosi; Amer, Aya; Kanhaiya, Pritpal; Srimani, Tathagata; Bishop, Mindy D.; Fuller, Samuel; Wright, Andrew; Lau, Christian; Hills, Gage (August 2019). "Modern microprocessor built from complementary carbon nanotube transistors". Nature. 572 (7771): 595–602. Bibcode:2019Natur.572..595H. doi:10.1038/s41586-019-1493-8. ISSN 1476-4687. PMID 31462796. S2CID 201658375.
  8. "A Carbon Nanotube Microprocessor Mature Enough to Say Hello". IEEE Spectrum: Technology, Engineering, and Science News. Retrieved 19 September 2019.
  9. Stanford scientists create world's first carbon nanotube computer | The Verge
  10. An Early Look at the Carbon Nanotube Computer Your Kids Will Use


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