A team of scientists at the Max Planck Institute of Quantum Optics recently demonstrated a record-breaking experiment that could rock the quantum computing industry.
The Quantum Slalom
One of the biggest challenges STEM researchers face today is the difficulty of building a fault-tolerant, stable quantum computer.
In essence, modern physicists flit between trying to scale quantum computers to functional dimensions and trying to suppress all the noisy errors as the systems grow.
When it comes to qubits, the quantum equivalent of computer bits, bigger is usually better. But it’s also much noisier.
The main reason for this is that it is incredibly difficult to reliably produce qubits without relying on random states – this is called the probabilistic method: for generating qubits.
Essentially, scientists just mix things up until the desired result emerges.
The researchers at the Max Planck Institute for Quantum Optics took a different route.
According to their newspaper:
We have presented a scalable and freely programmable source of entangled photons, demonstrating – to our knowledge – the largest entangled states of optical photons to date. It is deterministic in that it does not require probabilistic entanglement gates. This gives us a clear advantage of scale compared to previous schemes.
Let’s dive in
Quantum computing relies on entanglementthat is when two or more objects are prepared in such a way that whatever happens to one affects the other without regard for distance.
Usually photons (individual units of light) are entangled in a special kind of crystal. This results in a kind of entanglement that is relatively unpredictable. Scientists struggle to generate qubits effectively with this method because it is probabilistic.
The Max Planck team did away with the crystal creation chamber and instead turned a single atom into an entangled photon generator.
Per a press release from the Max Planck Institutes:
The researchers generated up to 14 entangled photons in an optical resonator, which can be primed to specific quantum physical states in a targeted and highly efficient manner. The new method could facilitate the construction of powerful and robust quantum computers and serve the secure transfer of data in the future.
The team managed to beat the previous record of 12 entangled photons using this method and they reached generation levels of almost 50%.
In other words, they were able to generate stable entangled photons almost half the time. This allowed them to take longer, more accurate measurements on the photons themselves.
This could very well be a “eureka moment” similar to Google’s recent discovery of time crystals.
According to the researchers, this technique for generating stable qubits could have huge implications for the whole field of quantum computing, but especially for scalability and noise reduction:
At this stage, our system mainly has to deal with technical limitations, such as optical losses, finite cooperativity and imperfect Raman pulses. Even modest improvements in these respects would put us within the range of loss and fault tolerance thresholds for quantum error correction.
It will take some time to see how well this experimental generation of qubits translates into a real computing device, but there’s plenty of reason to be optimistic.
There are numerous different methods by which qubits can be created, and each has its own unique machine architecture. The advantage of this is that the scientists were able to generate their results with a single atom.
This indicates that the technique would also be useful outside the computer. For example, if it could be developed into a two-atom system, it could lead to a new method of secure quantum communication.