Topological quantum computation based on chiral majorana fermions. The proposal relies on the existence of topological states of matter whose quasiparticle excitations are neither bosons nor fermions, but a re particles known as nonabelian anyons, meaning that they obey nonabelian braiding statistics. Nearly two years ago, ibm made a quantum computer available to the world. So its the highest temperature 2d topological insulator so far, says postdoc sanfeng wu, who also was a first author of the earlier paper. Quantum computing is the use of quantum mechanical phenomena such as superposition and entanglement to perform computation. Abstract for topological quantum computing for beginners, by john preskill i will describe the principles of faulttolerant quantum computing, and explain why topological approaches to fault tolerance seem especially promising. First twodimensional material that performs as both. Mathematics of topological quantum computing microsoft research. A pivotal goal of this research has been to realize materials hosting majorana quasiparticles, thereby making topological quantum computing a technological reality. The topological quantum computation model is eciently equivalent to other models of quantum computation such as the quan tum circuit model in the sense that all models solve the same class of problems in polynomial time fklw. In topological quantum computing, information is encoded in knotted quantum states of topological phases of matter, thus being locked into topology to prevent decay. With an emphasis on introduction to basic notions and current research, the book is almost entirely about the mathematics of topological quantum computation.
The braiding and fusion of anyonic excitations in quantum hall electron liquids and 2dmagnets are modeled by modular functors, opening a new. The toric code 7 was the first topological quantum error correction. Physical applications of topological quantum field theory topological quantum computing lukas hahn 1 introduction1 2 qubits and universality1 3 simulating quantum physics6 4 abstract anyonsense. In topological quantum computing, information is encoded in. Im typing as we go so please forgive all typos and unclear parts etc. The computational answer is accessed by bringing anyons together and observing the result. Topological quantum computationfrom basic concepts to. A twodimensional medium that supports abelian anyons has a topological. By the end of the book, readers understand that quantum computing and classical computing are not two distinct disciplines, and that quantum computing is the fundamental form of computing. Oct 23, 2018 as an essential step toward topological quantum computing, the braiding of mzms has not yet been experimentally demonstrated. A short introduction to topological quantum computation. Topological quantum computing avoids these problems by making the state immune to most types of noise.
Quantum computational approaches improve upon classical methods for a number of special ized tasks. Topological quantum materials for realizing majorana. The focus of the topological quantum computing roadmap is to develop, build and demonstrate the first topologically protected quantum bit based on majoranabound states. Physics copyright 2020 manybody topological invariants. Spacetime trajectories of anyons will be represented by braids, and more general quantum processes, such as creation. Topological quantum computing topological phases of matter are quantum computers, and form the foundation for building a scalable universal quantum computer. Depth optimization for topological quantum circuits. A s condensedmatter analogs of majoranafermions particles that are their own antiparticles 1majorana bound states mbss are anticipated to exhibit nonabelian exchange statistics, providing a basis for naturally faulttolerant topological quantum computing 27. The application of topology to physics has become an integral part of a second quantum revolution in the sciences. Nonetheless, certain algorithms may be a more natural fit to the topological quantum computer model.
One salient feature of tqc is the extensive use of graphical calculus. Ascr report on quantum computing for science sponsored by. It advertised a series of lectures by michel devoret, a wellknown expert on experimental efforts in quantum computing. In this book, the author presents a variety of different topics developed together for the first time. Despite a plethora of promising visions towards application and implementation, a number of serious challenges remain. We continued our efforts in combining material science, theory, and novel device design to obtain more control of the underlying constituents of. In order to motivate the development of topological quantum computing we begin by discussing typical quantum computing its problems. Majorana bound state in a coupled quantumdot hybrid. He defines quantum gates, considers the speed of quantum algorithms, and describes the building of quantum computers. At microsoft, the development of the topological qubit continues, bringing us closer to scalable quantum computing and finding solutions to some of the worlds most challenging problems. A promising technology is the quantum computers, and this paper gives a general overview about this subject. That is, any of these models can efficiently simulate any of the others. The theory of quantum computation can be constructed from the abstract study of anyonic systems. We will then introduce the concept of anyons as a generalization of bosons and fermions.
The process of building a quantum computer includes creating the raw materials needed to make topological quantum devices, fabricating the cold electronics and refrigeration systems, and developing the overall infrastructure needed to bring the solution to life. Pdf combining physics, mathematics and computer science, topological quantum computation is a rapidly expanding research area focused. The characterization and identification of topological phases in an experimental setting represents, however, a substantial challenge. Our algorithm shows that you dont need a big quantum computer to kick some serious topological butt, he says. Although quantum computing is still in its infancy, experiments have been carried out in which quantum computational operations were executed on a very small number of qubits quantum binary. The microsoft approach to quantum computing microsoft. Topological quantum computing has the promise of reaching up to six or seven nines, which means we wouldnt need to have this. This quantum spin hall effect persisted up to a temperature of about 100 kelvins 279. Oct 21, 2016 inside microsofts quest for a topological quantum computer. The topological qubit achieves this extra protection in two different ways. The synthesis of the two ideas ushered in topological quantum computation.
Introduction to topological quantum computation theoretical. We take a foundational approach, showing how knots are related not just to braiding and quantum operators, but to quantum set theoretical foundations and. I will not be as precise as mathematicians usually want. As an essential step toward topological quantum computing, the braiding of mzms has not yet been experimentally demonstrated.
The josephson junction is the basic building block of a superconducting qubit, and thus a quantum computer. Aug 16, 2017 that ceiling may soon crumble howevervaulting topological qubits into a fascinating new chapter in the quest for scalable quantum hardware. Topological quantum computation based on chiral majorana. Microsoft doubles down on quantum computing bet the ai blog. Topological quantum computing with majorana fermions. Topological quantum computing the focus of the topological quantum computing roadmap is to develop, build and demonstrate the first topologically protected quantum bit based on majoranabound states. Pdf photonic topological quantum computer george rajna. The braiding and fusion of anyonic excitations in quantum hall electron. This topological property is always present in the material at cold temperatures.
Combining physics, mathematics and computer science, topological quantum computation is a rapidly expanding research area focused on the exploration of quantum evolutions that are immune to errors. Combining the results together, we obtain an equivalence of the topolog. Nov 20, 2016 microsoft is doubling down on its commitment to the tantalizing field of quantum computing, making a strong bet that it is possible to create a scalable quantum computer using what is called a topological qubit. We continued our efforts in combining material science, theory, and novel device design to obtain more control of the underlying constituents of the topological qubit. An approach based on topological techniques reduces the sensitivity to errors and boosts the prospects for building practical quantum computers. Mathematics of topological quantum computing article pdf available in bulletin of the american mathematical society 552 may 2017 with 403 reads how we measure reads. Jan 25, 2016 solving the same problem with the new system, using a quantum computer, would require just 300 quantum bits and a device this size may be achieved in the next few years, according to lloyd. A topological quantum computer is a theoretical quantum computer that employs twodimensional quasiparticles called anyons, whose world lines pass around one another to form braids in a threedimensional spacetime i. Apr 23, 20 topological codes are an elegant and practical method for representing information in a quantum computer. Pdf classical and quantum computation download full. Such phases allow for quantum information to be stored and manipulated in a nonlocal manner, which protects it from imperfections in the implemented protocols and from interactions with the environment.
Time crystals and topological superconductors merge 12 february 2020, by anna demming. The future of quantum computing could depend on this tricky qubit. A gentle introduction eleanor rieffel and wolfgang polak. Topological quantum computation aims to achieve this goal by using nonabelian quantum phases of matter. Inside microsofts quest for a topological quantum computer. Gil kalais argument against quantum computers quanta.
Quantum computing qubits quantum decoherence noise extremely fragile need to be shielded from environmental perturbations topological quantum computing topological qubits based on nonabelian anyons these twodimensional quasiparticles form braids which are much more stable. Topological quantum computing has the promise of reaching up to six or seven nines, which means we. Thus, the world lines of two anyons cannot intersect or merge, which allows their paths to form stable braids in. In the past decade, basic physics, chemistry, and materials science research on topological quantum materialsand their potential use to implement reliable quantum computershas rapidly expanded to become a major endeavor. Topological quantum computing with a very noisy network and. Quantum computing is plagued by noise and small errors.
In this approach, information is stored in the lowest energy states of manyanyon systems and processed by braiding nonabelian anyons. Hastings, matthias troyer as quantum computing technology improves and quantum computers with a small but nontrivial number of n 100 qubits appear feasible in the near future the question of possible. Topological quantum computation is a computational paradigm based on topological phases of matter, which are governed by topological quantum field theories. A complete quantum system from hardware to software. On the another hand, when it comes to the realization of quantum computers in the applications of topological. Topological quantum computation purdue engineering. Topological quantum computation microsoft research. Computers that perform quantum computation are known as a quantum computers i5 quantum computers are believed to be able to solve certain computational problems, such as the integer factorization that underlies rsa encryption, significantly faster than. Mathematics of topological quantum computing american. December, 20 one of the main problems with experimental realizations of quantum computation is performing the required operationsresiliently. Longtime microsoft executive todd holmdahl who has a history of successfully bringing seemingly magical research projects to life as.
Alan aspuruguzik, wim van dam, edward farhi, frank gaitan, travis humble, stephen jordan, andrew landahl, peter love, robert lucas, john preskill, richard. When applied to quantum computing, topological properties create a level of protection that helps a qubit retain information despite whats happening in the environment. Schematic of one of the scalable architectures for topological quantum computation proposed by karzig and colleagues. Pdf introduction to topological quantum computation. The discovery of topological insulators and progress towards topological superconductors realizing nonabelian statistics has moved topological phases of matter onto the center stage in the interaction of topology and physics beyond the quantum hall effect. Topological properties are unchanged by small perturbations, leading to a builtin resistance to errors such as those caused by stray interactions with the surrounding environment. Time crystals and topological superconductors merge. A roadmap for a scalable topological quantum computer. Building qubits phase across junction energy maximum 0 energy energy minimum energy diagram of a junction electrons weak link superconductor what are the basic principles. Topological quantum computers are equivalent in computational power to other standard models of quantum computation, in particular to the quantum circuit model and to the quantum turing machine model. Even a small perturbation from the environment can have catastrophic effects on the quantumness of the system, which is precisely what were interested in with quantum computing. A circuit implemented under tqc is optimized by reducing its depth due to special construction.
Here we show that the propagation of chiral majorana fermions leads to the same unitary transformation as that in the braiding of majorana zero modes and propose a platform to perform quantum computation with chiral majorana fermions. Mathematics of topological quantum computing microsoft. The extent of quantum computing s applicability is still being determined. This paper is an introduction to relationships between quantum topology and quantum computing. Topological quantum computation is an approach to storing and. Quantum computing and topological qubits explained clearly. They underlie the jones polynomial and arise in wittenchernsimons theory. Scientists have developed a topological photonic chip to process quantum information, promising a more robust option for scalable quantum computers.
Can quantum chemistry be performed on a small quantum computer. In mathematical terms, these are unitary topological modular functors. An alternative design is the socalled topological quantum computer, which would use a radically different physical system to implement quantum computation. The future of quantum computing could depend on this tricky. Follow along on our journey to scalable quantum computing by signing up for the microsoft quantum. The fundamental constants h and e combine to form a quan tum of resistance he2. A topological approach to quantum mechanics and the philosophy of nature. In this work, we propose a hybrid approach that combines a leftedge greedy heuristic with genetic algorithm ga to minimize circuit depth through combined line and. This dear colleague letter dcl is intended to challenge the fundamental research community to achieve the transformative experimental realization of topological quantum computing. Introduction to topological quantum computation with nonabelian. In this survey, we discuss the conceptual development of.
A circuit implemented under tqc is optimized by reducing its depth due to special construction requirements in such technology. Quantum topological states of matter with applications in solid state physics, quantum computing, and quantum information theory a white paper on applications of m. Topological quantum computation tqc is a paradigm that information is en coded in topological degrees of freedom of certain quantum systems, thereby pro tected from local decoherence. One of the main challenges in condensed matter physics is the exploration of topological phases of matter that could be used to build a scalable quantum computer. Pdf knot logic and topological quantum computing with. We introduce anyons at the systemindependent level of anyon models and discuss the key concepts of protected fusion spaces and statistical quantum evolutions for encoding and processing quantum information.
After decades of heavy slog with no promise of success, quantum computing is suddenly buzzing with almost feverish excitement and activity. However, the computing process of a topological quantum computer heavily relies on the properties of the specific particle used, thus it is a vital part of the explanation. Quantum states tend to be confined to small scales and low temperatures, because interaction with large and warm systems will destroy them. The units of information, or logical qubits, are encoded as collective states in an array. Topological quantum computing kyle evitts introduction quantum computers have generated a lot of interest in the academic world, security circles, and tech companies because of their computational advantages over classical com. Kitaev, faulttolerant quantum computation by anyons. Nonabelian anyons and topological quantum computation. Nov 12, 2014 topological quantum computing tqc model is one of the most promising models for quantum computation. Similarly, not long after the first observations of topological insulators in the late 2000s, the.
Quantum computing is based on the ability to generate, manipulate, read, entangle and write quantum states of physical qubits. Topological quantum computation using majorana fermions. They found that a conventional quantum computer device, given an errorfree operation of its logic circuits, will give a solution with an absolute level of accuracy, whereas a topological quantum computing device with flawless operation will give the solution with only a finite level of accuracy. Topological quantum computers use particles with exotic exchange statis. Sep 22, 2011 topological quantum computing evades this barrier by exploiting topological materials that by their nature limit errors. In quantum computing, the application of topology is most interesting because the simplest nontrivial example of the temperleylieb recoupling theory gives the socalled fibonacci model.
In this paper, we propose a platform to implement topologically protected quantum gates at mesoscopic scales, which uses propagation of chiral majorana fermions with purely electrical manipulations instead of mzms. Topological quantum computation zhenghan wang ucsb math. Topological quantum computation has recently emerged as one of the most exciting approaches to constructing a faulttolerant quantum computer. Among these, topological states have become a major research direction in the past decade, from quantum spin liquids, to topological insulators and superconductors, to examples in photonics and mechanical systems. The abcs of topological quantum computing we introduce three basic notions in topological quantum computing tqc. Groups of particles similarly have quantum numbers topological quantum numbers. On the another hand, when it comes to the realization of quantum computers in the applications of topological theory for anyons, the. Qubits 1 introduction throughout the seminar, we encountered tqfts with anyonic excitations in various.
Jan 04, 2001 the theory of quantum computation can be constructed from the abstract study of anyonic systems. Topological precision has been confirmed in quantum hall liquids by experiments to an accuracy of 1010, and harnessed to stabilize quantum memory. Topological quantum computing tqc model is one of the most promising model for quantum computation. This insight put the study of anyons at the center of topological quantum computation.