With dispersion engineering and optimization of pump wavelength, four-wave mixing within a microstructured fiber can be used to produce high-purity entangled photons for applications in quantum information processing tasks.

Quantum information science provides unprecedented improvements in information processing and is moving out of the laboratory. Large-scale systems consisting of hundreds of quantum bits (qubits) are being built to conduct quantum computational tasks. With communication security dictated by the laws of quantum mechanics (rather than simply relying on the fact that cracking current communications systems is a very difficult and time-consuming task), several secure quantum networks are being built in China, Japan, Europe, and the United States.

Besides investment from government, the private sector is also expressing strong interest in secure quantum communications that transport signals thousands of miles across single-mode optical fiber (SMF) to deliver secure information between users.

Compared to atomic qubits, photonic qubits possess unique advantages. Resistant to many decoherence mechanisms and acting as the fastest information carriers, photonic qubits are inarguably the choice to carry information to a remote location, ending with detection or conversion into atomic-stationary qubits.

Periodically poled lithium niobate (PPLN) waveguide frequency-conversion devices have advantages over their bulk counterparts.

The UK believes it has a major global lead in the development of quantum clocks and sensors for navigation.

The quantum research is delivering stability and accuracy four orders of magnitude better than other systems, says Stephen Timms, fellow at the UK DSTL which is part of the Ministry of Defence. This will allow tradeoffs for smaller, chip scale devices, he says and more accurate control of systems.

The cryptographic systems that help protect digital transactions rely on random numbers, which are used to create “keys” to encrypt and decrypt confidential data. However, “if you want to break these cryptographic systems, the random number generator is one of the weakest links,”

One could produce truly random numbers by monitoring intrinsically random quantum phenomena, such as when radioactive atoms decay. Now Sanguinetti and his colleagues reveal that smartphone cameras can serve as the basis of such a quantum random number generator.

The scientists experimented with an eight-megapixel camera from a Nokia N9, which like many smartphone cameras is sensitive enough to count the exact number of photons that strike each of its pixels. They illuminated the camera with a conventional LED. Due to quantum mechanics, the number of photons most light sources generate over any given time is random. Since the number of photons the camera’s pixels detects is random, it serves as the basis of the quantum random number generator.

If an atom gets excited in a laboratory, does it make a sound? Turns out that it absolutely does, albeit it’s the softest sound that scientists say is physically possible.

So, why do this? For one, the team wanted to simply see if it could capture the softest sound ever made, which is certainly a noble goal. But, secondly, the researchers wanted to explore the quantum nature of sound. Photons (particles of light) have always been used in quantum experiments, but they’re pretty hard to manipulate because they’re so fast.

“The slow speed means that qubits can be tuned much faster [than photons] … this enables new dynamic schemes for trapping and processing quanta.”

In other words, perhaps the future of quantum communications isn’t in quantum light, it’s in quantum sound: “You have time to modify the signal when it propagates,”