Majorana 1#Topoconductors

Quantum computing research has historically faced challenges in achieving qubit stability and scalability. Traditional qubits, such as those based on superconducting circuits or trapped ions, are highly susceptible to noise and decoherence, which can introduce errors in computations. To overcome these limitations, researchers have been exploring various approaches to building more robust and fault-tolerant quantum computers. Topological qubits, first theorized in 1997 by Alexei Kitaev and Michael Freedman,{{Cite journal |last=Kitaev |first=A.Yu. |date=January 2003 |title=Fault-tolerant quantum computation by anyons |url=https://doi.org/10.1016/s0003-4916(02)00018-0 |journal=Annals of Physics |volume=303 |issue=1 |pages=2–30 |doi=10.1016/s0003-4916(02)00018-0 |arxiv=quant-ph/9707021 |bibcode=2003AnPhy.303....2K |issn=0003-4916}}{{Cite journal |last=Freedman |first=Michael H. |date=1998-01-06 |title=P/NP, and the quantum field computer |journal=Proceedings of the National Academy of Sciences |volume=95 |issue=1 |pages=98–101 |doi=10.1073/pnas.95.1.98 |doi-access=free |pmc=18139 |pmid=9419335|bibcode=1998PNAS...95...98F }} offer a promising solution by encoding quantum information in a way that is inherently protected from environmental disturbances. This protection stems from the topological properties of the system, which are resistant to local perturbations. Microsoft's approach, based on Majorana fermions in semiconductor-superconductor heterostructures, is one of several efforts to realize topological quantum computing.

Microsoft's quantum hardware has been the subject of controversy since its high-profile retracted article from Nature in 2018,{{Cite journal |last1=Zhang |first1=Hao |last2=Liu |first2=Chun-Xiao |last3=Gazibegovic |first3=Sasa |last4=Xu |first4=Di |last5=Logan |first5=John A. |last6=Wang |first6=Guanzhong |last7=van Loo |first7=Nick |last8=Bommer |first8=Jouri D. S. |last9=de Moor |first9=Michiel W. A. |last10=Car |first10=Diana |last11=Op het Veld |first11=Roy L. M. |last12=van Veldhoven |first12=Petrus J. |last13=Koelling |first13=Sebastian |last14=Verheijen |first14=Marcel A. |last15=Pendharkar |first15=Mihir |date=April 2018 |title=RETRACTED ARTICLE: Quantized Majorana conductance |url=https://www.nature.com/articles/nature26142 |journal=Nature |language=en |volume=556 |issue=7699 |pages=74–79 |doi=10.1038/nature26142 |pmid=29590094 |arxiv=1710.10701 |issn=1476-4687}}{{Retracted|doi=10.1038/s41586-021-03373-x|pmid=33686283|http://retractionwatch.com/2021/03/08/authors-retract-nature-majorana-paper-apologize-for-insufficient-scientific-rigour/ Retraction Watch|intentional=yes}} and the announcement of Majorana 1 has generated both excitement and skepticism within the scientific community.{{Cite news |last=Metz |first=Cade |date=2025-02-19 |title=Microsoft Says It Has Created a New State of Matter to Power Quantum Computers |url=https://www.nytimes.com/2025/02/19/technology/microsoft-quantum-computing-topological-qubit.html |access-date=2025-02-20 |work=The New York Times |language=en-US |issn=0362-4331}}{{Cite web |title=Microsoft Claims Quantum Breakthrough with Majorana 1 but Experts Aren't Convinced |url=https://www.ctol.digital/news/microsoft-quantum-breakthrough-majorana-1-expert-skepticism/ |access-date=2025-02-20 |website=CTOL digital |language=en}} A work related to Microsoft’s quantum chip from Nature Communications in 2017{{Cite journal |last=Zhang |first=Hao |last2=Gül |first2=Önder |last3=Conesa-Boj |first3=Sonia |last4=Nowak |first4=Michał P. |last5=Wimmer |first5=Michael |last6=de Vries |first6=Folkert K. |last7=van Veen |first7=Jasper |last8=de Moor |first8=Michiel W. A. |last9=Bommer |first9=Jouri D. S. |last10=van Woerkom |first10=David J. |last11=Car |first11=Diana |last12=Plissard |first12=Sébastien R. |last13=Bakkers |first13=Erik P. A. M. |last14=Quintero-Pérez |first14=Marina |last15=Cassidy |first15=Maja C. |date=2017-07-06 |title=Ballistic superconductivity in semiconductor nanowires |url=https://www.nature.com/articles/ncomms16025 |journal=Nature Communications |language=en |volume=8 |issue=1 |pages=16025 |doi=10.1038/ncomms16025 |issn=2041-1723|arxiv=1707.03024 }} has been brought into question, due to alleged undisclosed data processing.{{Cite web |title=‘Data manipulations’ alleged in study that paved the way for Microsoft’s quantum chip |url=https://www.science.org/content/article/data-manipulations-alleged-study-paved-way-microsoft-s-quantum-chip |access-date=2025-06-02 |website=www.science.org |language=en}}

In the announcement of Majorana 1, the hardware device was described as "the world’s first Quantum Processing Unit (QPU) powered by a Topological Core".{{Cite web |last=Nayak |first=Chetan |date=2025-02-19 |title=Microsoft unveils Majorana 1, the world's first quantum processor powered by topological qubits |url=https://azure.microsoft.com/en-us/blog/quantum/2025/02/19/microsoft-unveils-majorana-1-the-worlds-first-quantum-processor-powered-by-topological-qubits/ |access-date=2025-02-20 |website=Microsoft Azure Quantum Blog |language=en-US}} The hardware demonstrations currently available only demonstrate a method for readout, and do not demonstrate any quantum processing on the zero-mode. Moreover, the publicly available demonstration does not test coherence of their two-level quantum system. This is in contrast to other QPUs, which typically demonstrate both coherent quantum information and coherent logical operations on that quantum information.{{Cite web |date=2024-12-09 |title=Meet Willow, our state-of-the-art quantum chip |url=https://blog.google/technology/research/google-willow-quantum-chip/ |access-date=2025-02-20 |website=Google |language=en-us}}{{Cite web |title=System Model H2 {{!}} Quantinuum's Quantum Computers |url=https://www.quantinuum.com/products-solutions/quantinuum-systems/system-model-h2 |access-date=2025-02-20 |website=Quantinuum |language=en}}{{Cite web |title=Aquila {{!}} 256-qubit Quantum Computer |url=https://www.quera.com/aquila |access-date=2025-02-20 |website=QuEra |language=en}}

In their February 2025 press release, Microsoft claimed that "The Nature paper marks peer-reviewed confirmation that Microsoft has... been able to create Majorana particles". This is in contrast to the content of the Nature paper, in which the authors state that the measurements "do not, by themselves, determine whether the low-energy states detected by interferometry are topological".{{cite journal |collaboration=Microsoft Azure Quantum |first1=Morteza |last1=Aghaee |title=Interferometric single-shot parity measurement in InAs–Al hybrid devices |journal=Nature |volume=638 |date=2025 |issue=8051 |doi=10.1038/s41586-024-08445-2 |pmid=39972225 |at=Discussion and outlook: 1st paragraph|pmc=11839464 |arxiv=2401.09549 |bibcode=2025Natur.638..651M }}{{Cite journal |last=Castelvecchi |first=Davide |date=2025-02-19 |title=Microsoft claims quantum-computing breakthrough — but some physicists are sceptical |url=https://www.nature.com/articles/d41586-025-00527-z |journal=Nature |volume=638 |issue=8052 |page=872 |language=en |doi=10.1038/d41586-025-00527-z|pmid=39972094 |bibcode=2025Natur.638..872C |url-access=subscription }}

The reason for the uncertainty is the difficulty in distinguishing Majorana modes and Andreev modes.{{Cite journal |last1=Kells |first1=G. |last2=Meidan |first2=D. |last3=Brouwer |first3=P. W. |date=2012-09-12 |title=Near-zero-energy end states in topologically trivial spin-orbit coupled superconducting nanowires with a smooth confinement |url=https://doi.org/10.1103/physrevb.86.100503 |journal=Physical Review B |volume=86 |issue=10 |page=100503 |doi=10.1103/physrevb.86.100503 |arxiv=1207.3067 |bibcode=2012PhRvB..86j0503K |issn=1098-0121}} Both types of modes can exist in the sorts of devices that Microsoft is constructing. The Majorana modes are topological and could potentially be used for making a topological quantum computer, but the Andreev modes are topologically trivial and are not directly useful for making a quantum computer. The current results of Majorana 1 are completely consistent with the possibility that the device consists of Andreev modes, and does not contain any Majorana modes.

The difficulty in distinguishing between Majorana modes and other topologically trivial possibilities like Andreev modes was also the source of the high-profile Nature retraction in 2018. In this article the authors, which were affiliated with Microsoft, claimed to have conclusive evidence of Majorana zero modes, but the data was shown to be entirely consistent with Andreev modes.{{Cite magazine |last=Simonite |first=Tom |title=Microsoft-Led Team Retracts Disputed Quantum-Computing Paper |url=https://www.wired.com/story/microsoft-retracts-disputed-quantum-computing-paper/ |access-date=2025-02-20 |magazine=Wired |language=en-US |issn=1059-1028}}{{Cite journal |last=Castelvecchi |first=Davide |date=2021-03-10 |title=Evidence of elusive Majorana particle dies — but computing hope lives on |url=https://www.nature.com/articles/d41586-021-00612-z |journal=Nature |language=en |volume=591 |issue=7850 |pages=354–355 |doi=10.1038/d41586-021-00612-z|pmid=33692528 |bibcode=2021Natur.591..354C }}

In their February 2025 press releases, Microsoft claimed that the Majorana 1 hardware device created "a new state of matter that previously existed only in theory." This is in contrast to the long history of experiments based on semiconducting nanowires in similar regimes to the one exhibited by the Majorana 1 chip,{{Cite conference |last1=Wei |first1=Peng |last2=Manna |first2=Sujit |last3=Xie |first3=Yingming |last4=Law |first4=Kam Tuen |last5=Lee |first5=Patrick |last6=Moodera |first6=Jagadeesh |date=20 August 2020 |editor-last=Drouhin |editor-first=Henri-Jean M. |editor2-last=Wegrowe |editor2-first=Jean-Eric |editor3-last=Razeghi |editor3-first=Manijeh |title=The demonstration of Majorana zero modes in scalable gold nanowires |conference=Spintronics XIII |publisher=SPIE |volume=11470 |pages=114700L |doi=10.1117/12.2565976 |isbn=978-1-5106-3746-7}} which should putatively be in the same state of matter. This is highlighted in the peer review file for Microsoft's Majorana 1 paper, where one reviewer describes the paper by saying that "the novelty of this manuscript does not lie in providing stronger evidence for [Majorana Zero modes], but in its methodological approach: it demonstrates that rf-parity readout 'can be done' within [a] complicated loop geometry". Despite a split among the four reviewers, with two expressing reservations and two offering conditional support, Nature published the paper, basing its decision on the innovative device architecture rather than on definitive evidence for Majorana modes.{{Cite journal |title='Interferometric Single-Shot Parity Measurement in InAs-Al Hybrid Devices' Peer Review File |url=https://static-content.springer.com/esm/art:10.1038/s41586-024-08445-2/MediaObjects/41586_2024_8445_MOESM2_ESM.pdf |journal= Nature|date=2025 |doi=10.1038/s41586-024-08445-2 |pmid=39972225 |archive-url=http://web.archive.org/web/20250219164959/https://static-content.springer.com/esm/art%3A10.1038%2Fs41586-024-08445-2/MediaObjects/41586_2024_8445_MOESM2_ESM.pdf |archive-date=2025-02-19 |last1=Microsoft Azure |first1=Quantum |last2=Aghaee |first2=M. |last3=Alcaraz Ramirez |first3=A. |last4=Alam |first4=Z. |last5=Ali |first5=R. |last6=Andrzejczuk |first6=M. |last7=Antipov |first7=A. |last8=Astafev |first8=M. |last9=Barzegar |first9=A. |last10=Bauer |first10=B. |last11=Becker |first11=J. |last12=Bhaskar |first12=U. K. |last13=Bocharov |first13=A. |last14=Boddapati |first14=S. |last15=Bohn |first15=D. |last16=Bommer |first16=J. |last17=Bourdet |first17=L. |last18=Bousquet |first18=A. |last19=Boutin |first19=S. |last20=Casparis |first20=L. |last21=Chapman |first21=B. J. |last22=Chatoor |first22=S. |last23=Christensen |first23=A. W. |last24=Chua |first24=C. |last25=Codd |first25=P. |last26=Cole |first26=W. |last27=Cooper |first27=P. |last28=Corsetti |first28=F. |last29=Cui |first29=A. |last30=Dalpasso |first30=P. |volume=638 |issue=8051 |pages=651–655 |pmc=11839464 |arxiv=2401.09549 |bibcode=2025Natur.638..651M |display-authors=1 }}

Microsoft introduced the term topoconductor to describe the material on which Majorana 1 is based. In their February 2025 press release, Microsoft defined topoconductors as a "class of materials [which] enables... topological superconductivity". According to Microsoft, these materials are widely theorized to allow for the creation and manipulation of Majorana zero modes, which could then serve as the basis for topological qubits.{{Cite journal |last1=Fu |first1=Liang |last2=Kane |first2=C. L. |date=6 March 2008 |title=Superconducting Proximity Effect and Majorana Fermions at the Surface of a Topological Insulator |journal=Physical Review Letters |volume=100 |issue=9 |page=096407 |doi=10.1103/PhysRevLett.100.096407 |pmid=18352737 |arxiv=0707.1692 |bibcode=2008PhRvL.100i6407F |issn=0031-9007}}{{Cite journal |last1=Stoudenmire |first1=E. M. |last2=Alicea |first2=Jason |last3=Starykh |first3=Oleg A. |last4=Fisher |first4=Matthew P.A. |date=14 July 2011 |title=Interaction effects in topological superconducting wires supporting Majorana fermions |journal=Physical Review B |volume=84 |issue=1 |page=014503 |doi=10.1103/PhysRevB.84.014503 |arxiv=1104.5493 |bibcode=2011PhRvB..84a4503S |issn=1098-0121}} Topological superconductors are characterized by their unique electronic band structure, which gives rise to topologically protected surface states.{{Cite journal |last1=Sato |first1=Masatoshi |last2=Ando |first2=Yoichi |date=July 2017 |title=Topological superconductors: a review |journal=Reports on Progress in Physics |volume=80 |issue=7 |pages=076501 |doi=10.1088/1361-6633/aa6ac7 |pmid=28367833 |arxiv=1608.03395 |bibcode=2017RPPh...80g6501S |issn=0034-4885}} These surface states are robust against disorder and imperfections, making them ideal for hosting Majorana zero modes. Microsoft's topoconductor is made of indium arsenide and aluminum.{{Cite web |title=Microsoft's Big Bet on Majorana Pays Off with New Topological Quantum Chip |url=https://www.hpcwire.com/2025/02/19/microsofts-big-bet-on-majorana-pays-off-with-new-topological-quantum-chip/ |access-date=2025-02-19 |website=HPCwire}}

Internal whitepapers from Microsoft outline a topoconductor-based architecture which facilitates braiding processes—key operations for error-resistant qubit logic.{{Cite journal |last1=Alam |first1=Salman |last2=Najma |first2=Bibi |last3=Singh |first3=Abhinav |last4=Laprade |first4=Jeremy |last5=Gajeshwar |first5=Gauri |last6=Yevick |first6=Hannah G. |last7=Baskaran |first7=Aparna |last8=Foster |first8=Peter J. |last9=Duclos |first9=Guillaume |date=3 October 2024 |title=Active Fréedericksz Transition in Active Nematic Droplets |journal=Physical Review X |volume=14 |issue=4 |page=041002 |doi=10.1103/PhysRevX.14.041002 |bibcode=2024PhRvX..14d1002A |issn=2160-3308|doi-access=free }} Braiding involves exchanging the positions of Majorana zero modes in a controlled manner, which can be used to perform quantum computations. This process is inherently fault-tolerant because the topological protection of the Majorana modes makes them resistant to local disturbances.

• Quantum error correction
• Topological quantum field theory

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{{Microsoft}}

Category:Microsoft

Category:Quantum computing