Breakthroughs in Teleportation and Topological Qubits Bring Quantum Computing Closer to Reality

 

 

By James Myers

Numerous innovations over the past year indicate that the challenge of creating stable quantum computer circuits could soon be conquered, and two developments in recent weeks highlight how close to reality a network of fully-functional quantum computers is becoming.

Using the quantum phenomenon of entanglement, in which two particles connect so that both simultaneously carry the same information, scientists at the University of Oxford have achieved a breakthrough in quantum teleportation. Although the word teleportation might sound like a science fiction method of transporting matter, in quantum information processing it means the wireless transmission of data from one location to another.

While quantum teleportation had previously been demonstrated with the simple sending and receipt of a signal, the Oxford researchers were able to create interactions with the information transmitting between quantum processors separated by two metres. The achievement is a milestone in the creation of a ‘quantum internet’, which would connect quantum computers to combine and amplify their tremendous processing power.

 

 

Dougal Main, a PhD candidate in Physics at the University of Oxford who led the research, explained in a university press release that, “By carefully tailoring these interactions, we can perform logical quantum gates – the fundamental operations of quantum computing – between qubits housed in separate quantum computers. This breakthrough enables us to effectively ‘wire together’ distinct quantum processors into a single, fully-connected quantum computer.”

Enabling interactions between quantum computers will significantly increase the number of operations that can be performed by the networked machines. Currently, quantum computers are limited in their ability to process information because their circuits are fragile and prone to disconnection, or “decoherence,” from environmental disturbances.

In quantum computers, information is transmitted between qubits, the quantum analogue of bits that process data in computers commonly used around the world. The problem of decoherence has meant that only small numbers of qubits can be successfully connected in circuits, which so far has prevented the development of practical applications for the machines.

The qubit is far more versatile than the bit, which can be in only one state – either on or off – at a time. A qubit operates in both states simultaneously, which provides the quantum computer with incredible speed and accuracy. Increasing the numbers of connected qubits will bring the potential power of quantum computer closer to reality.

That power could lead to some amazing discoveries about the universe. In a November 2022 paper, scientists from MIT, Caltech, and Harvard University linked teleportation to the potential creation of wormholes using quantum computers in the distant future. Wormholes, first theorized by Albert Einstein and Nathan Rosen in 1935, could transfer quantum information between distant points in the universe.

 

 

In its press release on the latest discovery in teleportation, the University of Oxford stated,

“The breakthrough addresses quantum’s ‘scalability problem’: a quantum computer powerful enough to be industry-disrupting would have to be capable of processing millions of qubits. Packing all these processors in a single device, however, would require a machine of an immense size. In this new approach, small quantum devices are linked together, enabling computations to be distributed across the network. In theory, there is no limit to the number of processors that could be in the network.”

The teleportation was proven successful by the operation of Grover’s algorithm, a process for quantum computers that performs searches on large unstructured datasets far more quickly than the fastest bit-based computers now in operation. As the researchers reported in their paper, published in Nature, the logical connections maintained 86% fidelity, and Grover’s algorithm operated with a 71% success rate.

While individual quantum computers using the trapped-ion architecture of the Oxford researchers can achieve greater fidelity, the researchers concluded that with further development, “the technical limitations in our implementation can be overcome.”

Topological qubits: has Microsoft actually created them?

In another development, researchers at Microsoft claim to have created a different type of qubit called a “topological” qubit. Last February, in our article The Geometry of Information: Is Topological Quantum Computing the Future? we noted that a significant advantage of recording quantum information in a specific geometry, or topology, is the system-wide storing of data without the risk of errors from signal interference in particular sections of the system. 

 

 

Microsoft says that it has created several topological qubits and a method for deploying them in computations.

The company encoded information in tiny superconducting wires in a physical process that puts both ends of each wire in an identical state in a new phase of matter that is not solid, liquid, or gas. By connecting two wires, they created a qubit operating simultaneously in opposite states. 

Microsoft’s qubit is named for the quasiparticles, called Majorana quasiparticles after physicist Ettore Majorana, that it claims were created at each end of the superconducting wires. The two quasiparticles share an electron that responds to their combined state.

In a paper published on February 17 entitled Roadmap to fault tolerant quantum computation using topological qubit arrays, the Microsoft researchers state that their method provides advantages in the creation of “a utility-scale quantum computer of hundreds, if not thousands of logical qubits that is able to solve commercially relevant problems.” 

The paper states that the tiny size of each qubit would allow millions of them to fit on a single chip wafer, and manipulating the topological qubits requires a lower level of precision than standard qubits. 

 

 

Microsoft has not yet released performance data on its eight-qubit Majorana 1 chip, and its paper indicates that its measurements “do not unequivocally distinguish” between the expected state of the qubits and other possibilities. New Scientist reports there is some scepticism about Microsoft’s claims, based on the imprecision of the testing method and a breakthrough announcement on Majorana quasiparticles made by a Microsoft-funded team in 2018 that was retracted in 2021.

Microsoft says it has disclosed some of its data to selected specialists in a meeting at its research centre in Santa Barbara, California, although the company hasn’t yet released proof that it succeeded in creating topological qubits. Scientific American quotes a statement by Microsoft researcher Chetan Nayak, who said, “We are committed to open publication of our research results in a timely manner while also protecting the company’s IP [intellectual property].”

Nonetheless, the U.S. Defense Advanced Research Projects Agency announced that it has selected Microsoft’s topological superconductor method as one of the two potential pathways DARPA is assessing for the potential of creating an industrially useful quantum computer by 2033.

The road ahead to a fully functioning quantum computer is shorter than many had recently thought.

In October, The Quantum Record reported on the announcement by major quantum computing company Quantinuum that it intends to produce a fault-tolerant quantum computer before the end of 2029. In December, we reported on Google’s new quantum chip, named Willow, that the company said performed in five minutes a calculation that would have required ten septillion years on a supercomputer. 

 

 

Last year produced a record number of significant and breakthrough announcements in quantum computing that point to the technology’s full-scale introduction in the not too distant future. 

It would not be surprising, given the large numbers of students and scientists now engaged in the field, the significant investments being made by major companies like Quantinuum, Microsoft, Google, IBM, as well as the attention that quantum computing is receiving from many governments. China, for example, has announced $15.3 billion of commitments to quantum research, followed by the European Union which has committed $7.2 billion.

Our December feature, Is There a Looming Digital Divide With Quantum Technology? was the sixth part of our pioneering series on quantum ethics that raised many questions about humanity’s relationship with the new technology. As the delivery date for industrially useful, fault tolerant, and networked quantum computers approaches more rapidly, the questions of quantum ethics and the applications the machines will be used for are becoming increasingly urgent.

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