For the first time, scientists have successfully entangled a string of 14 photons that were released one after the other. All of the photons originated from the same excited atom. The scientists wrote in Nature that it was possible to regulate both its quantum states and the properties of the entangled photons. This carefully controlled mass generation of entangled photons may advance quantum computers and quantum communications.
Quantum computers and quantum communication are based on the entanglement phenomenon in quantum mechanics. This is due to the fact that only this coupling of states enables information to be conveyed very instantly or allows qubits to execute computations. Physicists have successfully entangled and transferred particles across vast distances in a variety of simultaneous states. However, the scalability of the controlled creation of entangled photons has thus far only been modest.
With the current technique, a higher energy photon is converted into an entangled pair of lower energy photons. However, it is challenging to use this technique to generate higher numbers of photons in a regulated manner.
An Atom Acting as an Emitter
Philip Thomas and his colleagues founded the Max Planck Institute of Quantum Optics in Garching, and they have now developed a technique that enables one atom to produce an entire chain of entangled photons. These photons’ quantum physical states can be precisely tuned and controlled during the process. Thus, the team successfully and precisely produced up to 14 entangled photons for the first time.
Thomas notes that the key to this experiment was the employment of a single atom to emit and selectively interweave the photons. He and his colleagues achieved this by positioning a rubidium atom in the middle of an optical cavity resonator, which functions as an electromagnetic wave’s echo chamber. They energized the atom and moved it into the required quantum state using laser light at a precise frequency.
An Entangled Photon Chain
The next crucial step was utilizing a second laser pulse to selectively activate a photon’s emission that was entangled with the appropriate quantum state of the atom. In a predetermined order, this operation was performed multiple times. In theory, the creation of one photon at a time alternates with the manipulation of the atom acting as a quantum bit.
The atomic rotations enabled the researchers to create a chain of up to 14 light particles, which were then entangled and brought into the required condition.
The 14 light atoms connected in this chain represent the most entangled photons ever created in a lab. According to this, the chain of photons can be formed deterministically since it came from a single atom.
Controllable and Effective
The team claims that this technique is also quite effective, which is crucial for upcoming technological applications. They were able to demonstrate an efficiency of close to 50% by doing measurements on the generated photon chain. As a result, much more useful, entangled photons were produced practically every second of “button pushing” on the rubidium atom than had been possible in earlier studies.
Overall, our approach eliminates a significant barrier to scalable, measurement-based quantum computing. The novel approach may aid in the development of powerful quantum computers as well as secure data transfer.
