TU Wien Research Paves Way for More Powerful Optical Quantum Computers
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Researchers at TU Wien, collaborating with a team in China, have achieved a significant advance in quantum computing by moving beyond the limitations of traditional qubits. Instead of relying on combinations of 0s and 1s, their new technology harnesses the power of qudits, utilizing four distinct quantum states simultaneously to perform computations. This breakthrough, detailed in a recent publication in Nature Photonics, centers on the realization of a novel quantum gate capable of processing pairs of photons in these higher-dimensional states—a crucial step for building more powerful optical quantum computers. “We use photons in a fundamentally different way,” explains Nicolai Friis from the Institute of Atomic and Subatomic Physics of TU Wien. “We aren’t interested in the polarization, but in the spatial wave form of the photons, which can be in infinitely many different states.” This innovation promises to unlock new opportunities in quantum computation by expanding the potential for complex calculations. Four-State Qudits Enable High-Dimensional Quantum Computation Quantum computation took a significant leap forward as researchers demonstrated a novel quantum gate utilizing four-dimensional qudits, exceeding the limitations of traditional two-state qubits. A collaborative effort between TU Wien and a Chinese research group has yielded a method for processing quantum information encoded in photons with unprecedented dimensionality, published in Nature Photonics. While conventional quantum computers rely on bits existing as 0 or 1, this new technology leverages the potential for quantum systems to exist in multiple states simultaneously, offering substantial computational advantages.
The team’s innovation centers on exploiting the spatial waveform of photons, rather than their polarization, to encode information. This allows for infinitely many potential states, a concept known as a qudit, and opens possibilities for more complex and efficient algorithms. The researchers successfully designed a scheme to jointly process two qudits encoded in photons, culminating in the creation of a new quantum gate capable of entangling and disentangling photons in a controlled manner. For their initial experiment, the team focused on manipulating photons across four distinct states, effectively operating within a four-dimensional space. “This is as if, in addition to the North-South and East-West directions, one would have access to two additional axes,” says Friis. Crucially, the process is “heralded,” meaning researchers can verify the success of the entanglement, and repeat the procedure if necessary—a vital characteristic for practical quantum computing. Marcus Huber notes that this approach offers a path to increased efficiency, stating, “We need fewer particles to carry the same amount of quantum information,” promising greater stability and reliability in quantum operations.
Entangled Photons Realize Novel Quantum Gate Protocol The pursuit of scalable quantum computing has long focused on refining the qubit, but researchers are increasingly exploring the potential of qudits—quantum systems leveraging more than two states—to enhance computational power and stability. Published in Nature Photonics, the work represents a crucial step toward optical quantum computers with expanded capabilities and improved efficiency. This innovation diverges from traditional photon-based quantum computing, which typically relies on polarization as the defining characteristic. The new gate facilitates the creation of entangled photon pairs, enabling complex calculations on multiple inputs. The experimental realization required substantial technological advancements, particularly in precision control and measurement. The process is notably “heralded,” meaning researchers can confirm successful entanglement. “We can tell, when the protocol worked. And if it did not, we can repeat the procedure. This is what is needed in practice,” Friis stated. We can entangle the photons-and we can do so in a heralded fashion, meaning that we can tell, when the protocol worked. And if it did not, we can repeat the procedure.
Nicolai Friis Heralded Operation Confirms Functional Quantum Logic Researchers affiliated with TU Wien, in close collaboration with a team in China, have demonstrated a functional quantum logic gate operating on photons encoded with significantly higher dimensionality than previously achieved. Unlike conventional experiments focusing on photon polarization, this approach manipulates the shape of the light itself, opening up possibilities for increased computational complexity. This verification is vital for practical applications, allowing for repeated attempts when the protocol fails. “We can entangle the photons—and we can do so in a heralded fashion, meaning that we can tell, when the protocol worked. This is as if, in addition to the North-South and East-West directions, one would have access to two additional axes Friis Source: https://www.tuwien.at/en/tu-wien/news/news-articles/news/quantencomputer-werden-viel-dimensional Tags: