The team LI Chengfeng, ZHOU Zongquan and others from CAS Key Lab of Quantum Information developed multi-degree-of-freedom (DOF) multiplexed solid-state quantum memory and demonstrate photon pulse operation functions with time and frequency DOFs. The result was published on Nature Communications recently.
The faithful storage and coherent manipulation of quantum states with matter-systems enable the construction of large-scale quantum networks based on quantum repeater. To achieve useful communication rates, highly multimode quantum memories will be required to construct a multiplexed quantum repeater.
The team presented the first demonstration of the on-demand storage of orbital-angular-momentum states with weak coherent pulses at the single-photon-level in a rare-earth-ion doped crystal. Through the combination of this 3-dimensional spatial degree-of-freedom with 2-dimensional temporal and 2-dimensional spectral degrees of freedom, the team created a multiple-DOF memory with high multimode capacity up to 3*2*2=12.
This device can also serve as a quantum mode converter with high fidelity, which is the fundamental requirement for the construction of a multiplexed quantum repeater.
The team further demonstrated that the device can perform arbitrary pulse operations within time and frequency DOF. Representative operations include pulses sequencer, multiplexer, selective spectral shifter and configurable beam splitter. The experimental results showed that in all these operations, the three-dimensional quantum states carried by photons maintained a fidelity of about 89%.
This memory device can realize all the operations required for Knill-Laflamme-Milburn type quantum computation, so this device is expected to find more applications in the field of linear optical quantum computing.