Quantum memory is a device that can store quantum information. It typically stores quantum information by absorbing photons with certain quantum states. The quantum memory then processes these quantum states and emits them as an output.
Quantum Memory & Entanglement
Quantum memory is a necessary part of quantum computers for long-distance communication. This is because quantum information can be entangled between different quantum memories. Entanglement allows quantum computers to communicate with each other over long distances.
However, if the entanglement between two quantum memories is broken, the device can no longer be used as quantum memory. Instead, it can only transmit information in the form of classical bits.
Working of Quantum Memory
It can also convert predetermined photons into on-demand photons. When a light pulse is incident on the quantum memory, it decomposes the light into a collective state of atomic groups on the optical transmission part. This is similar to the way a beam splitter works. The light is then mapped coherently with the state of the signal mode that emerges from the phase modulator. This creates atomic excitations.
Upon re-emission, the quantum memory again works like a beam splitter, mapping the collective atomic state to the optical mode. The quantum memory then returns to its prior state by the reduction of atomic excitations.
The storage time for this process is 50 nanoseconds, which is much shorter than the coherence time of 57 microseconds and the optical transition time of 300 microseconds. This means that the collective atomic states remain coherent throughout the whole process.
Optical Data Storage
Optical data storage is a type of quantum memory that uses light to store quantum information. This is done by encoding quantum information into the superposition of different light states.
The superposition of light states is a fragile state that cannot be observed by a hacker without destroying it. This makes optical data storage a very secure way to store quantum information.
In addition, optical data storage can also detect tampering with data. If a hacker tries to change the data stored in an optical memory, they will leave a trace behind. This trace can be used to detect the tampering and restore the data to its original state.
As a result of these features, optical data storage is a promising technology for protecting quantum information from hackers and thefts.