The field of quantum computing has long been dominated by the quest for faster and more efficient computational tools. Photonic quantum computers have emerged as promising alternatives due to their leverage of quantum physics and the use of photons as units of information processing. However, one of the major hurdles facing these computers is the inherently weak interactions between individual photons, hindering the realization of deterministic two-qubit gates essential for scalability.
Recent research published in Physical Review Letters by the University of Science and Technology of China sheds light on a potential solution to this challenge. By demonstrating a large cluster state capable of facilitating quantum computation in a photonic system, specifically three-photon entanglement, researchers have shown that fusion and percolation could be scalable approaches to realizing quantum computation without the need for deterministic entangling gates.
The study conducted by Hui Wang and his colleagues delves into the generation of the necessary resource state, with a focus on the three-photon Greenberger-Horne-Zeilinger (3-GHZ) state. Through the near-deterministic generation of entangled clusters in a heralded fashion, the researchers were able to create the 3-GHZ state from a single-photon source in a photonic chip. This method appears to be the most promising for achieving success in generating the required state for large-scale cluster states suitable for measurement-based quantum computing.
The experimental setup utilized by Wang and his team involved injecting six single photons into a 10-mode passive interferometer, with an overall efficiency of 50%. By applying a specific unitary transformation, they were able to manifest a dual-rail encoded heralded 3-GHZ state, dependent on the detection of single photons in specific ports.
The significance of this work lies in its contribution towards realizing fault-tolerant photonic quantum computing. The ability to generate and manipulate 3-GHZ resource states opens the door to the development of large-scale optical quantum computers capable of processing quantum information with unprecedented efficiency.
The recent study by Wang and his collaborators builds upon previous advances in the field of photonic quantum computing. The first report of heralded single photons dates back to 1986, while the first heralded entangled photon pairs were achieved in 2010. This latest research demonstrates a significant milestone in the development of large cluster states, paving the way for fault-tolerant, measurement-based quantum computing using photonic chips.
As technology continues to advance, the realization of fault-tolerant photonic quantum computers draws nearer. Wang envisions a future where the demonstration of a fusion gate surpassing the percolation threshold using eight single photons is well within reach. By amalgamating multiple 3-GHZ resource states, a more extensive entangled state could be formed, further advancing the capabilities of photonic quantum computing.
The research conducted by Wang and his team represents a significant step towards harnessing the power of photonic quantum computing. By leveraging fusion and percolation strategies, researchers are overcoming the limitations posed by weak interactions between photons, opening up new possibilities for the development of high-speed, long-distance quantum computers.