14 DAY TRIAL // According to a scientific paper appearing in this issue of the respected scientific journal Nature, experts at the university of California in Santa Barbara (UCSB) have recently managed a remarkable breakthrough in the field of quantum mechanics. They have succeeded in detecting the quantum correlations in the results of measurements of entangled quantum bits, or qubits. In their experiments, they report, a superconducting, electrical circuit was used, so that the results could be inferred.
The team also reveals that the obtained correlations are stronger than any of those obtained using conventional (non-quantum mechanical) physics. Additionally, and most importantly, the new UCSB study shows that the oddities that characterize the quantum world do not only take place at the small scale. They can affect the macroscopic world in equal proportion, the physicists say. The results were obtained by a joint collaboration of scientists from experts John Martinis and Andrew Cleland's laboratories at the university.
One of the basic properties of quantum mechanics is that measurements conducted in experiments have unpredictable results. In spite of this fact, the new investigation has proven, strong correlations still exist. By measuring, for example, quantum states – such as a system made up of two particles with opposite spins –, experts can now stringently test the discrepancies that occur between results obtained under classical and quantum physics. These discrepancies are described through the famous “Bell inequalities,” and measurements of their value are known as “Bell violations.”
What makes the new UCSB research so important is the fact that, for the first time, physicists have shown that a Bell inequality can, indeed, be violated with two entangled, superconducting qubits. In doing so, they also proved that such a macroscopic electrical circuit was, in fact, a quantum system. Martinis reveals that measuring Bell violations with qubits was to be the next primary challenge for the superconducting qubit community. However, it won't be necessary from now on, as this objective has already been achieved.
“This experiment has met this challenge, achieved by performing a very demanding measurement on a pair of Josephson qubits, a measurement that requires excellent control over qubit state preparation, qubit entanglement, and very high fidelity single-shot state measurements of the entangled qubits. It directly proves that quantum mechanics is the only possible description for the behavior of a macroscopic electrical circuit,” the expert concludes.