Disclosure of Invention
The invention aims to provide a low-temperature infrared filter which can filter out parasitic phonons and photon quasi-particles and protect qubits.
In order to achieve the purpose, the invention adopts the following technical scheme:
a low-temperature infrared filter comprises a filter cavity, a filtering component arranged in the filter cavity, and an input connector and an output connector which are respectively arranged at openings at two ends of the filter cavity; the filter assembly comprises an infrared absorption part filled in the cavity of the filter and an inner conductor which is arranged in the infrared absorption part in a penetrating way, and two ends of the inner conductor are respectively connected with the input connector and the output connector.
Furthermore, two end openings of the filter cavity are respectively provided with an insulating dielectric plate, and two ends of the inner conductor respectively penetrate through the two insulating dielectric plates and then are connected with the input joint and the output joint.
Furthermore, the infrared absorption part is positioned between the two insulating medium plates.
Furthermore, the infrared absorption part adopts castable epoxy resin wave-absorbing material.
Further, the inner conductor is made of beryllium bronze.
Furthermore, the insulating medium plate is made of polytetrafluoroethylene materials.
Further, the input connector and the output connector adopt any one of SMA, N or DIN connectors. Preferably, the input connector and the output connector adopt double-female SMA connectors.
Furthermore, the filter cavity is provided with an injection hole and a vent hole.
According to the technical scheme, the low-temperature infrared filter is added to the signal path, so that parasitic phonons and photon quasi-particles can be filtered, and the purpose of protecting qubits can be achieved. The low-temperature infrared filter can work below a liquid helium temperature region, and an infrared absorption part made of a high-matching castable epoxy resin wave-absorbing material with a proper dielectric constant is used as a main body of the filter, so that infrared waves mixed in a microwave communication transmission path can be effectively absorbed. And the device of the low-temperature infrared filter is small in size, easy to assemble and debug and stable in performance at low temperature, and can well meet the requirements of the current related systems.
Detailed Description
The invention is further described below with reference to the accompanying drawings:
as shown in fig. 1, the low-temperature infrared filter includes a filter cavity 3, a filter assembly installed in the filter cavity 3, and an input connector 1 and an output connector 2 respectively installed at openings at two ends of the filter cavity 3. The filtering component comprises an infrared absorption part 4 filled in the cavity of the filter and an inner conductor 6 which is arranged in the infrared absorption part 4 in a penetrating way and two ends of which are respectively connected with the input connector 1 and the output connector 2. The low-temperature infrared filter is used for filtering infrared light of bad quasi-particles generated in a signal path when a microwave communication system works.
Furthermore, two end openings of the filter cavity 3 are respectively provided with an insulating dielectric plate 5, and two ends of the inner conductor 6 respectively penetrate through the two insulating dielectric plates 5 and then are connected with the input connector 1 and the output connector 2.
Further, the infrared absorption part 4 is located between the two insulating dielectric sheets 5.
Further, the input connector 1 and the output connector 2 adopt any one of SMA, N or DIN connectors. Preferably, in order to reduce the size of the filter, the input connector 1 and the output connector 2 adopt double-negative SMA connectors.
Furthermore, the infrared absorption part 4 adopts a castable epoxy resin wave-absorbing material, and the mixing ratio of the material is related to the insertion loss and out-of-band rejection of the filter. Preferably, the castable epoxy resin wave-absorbing material adopts ECCOSORB CR series, and the castable epoxy resin wave-absorbing material has extremely low loss in a C wave band and sharply increases loss in a frequency band of Ka and above. According to the huge difference of the loss of the castable epoxy resin wave-absorbing material in the C wave band, the Ka wave band and the frequency bands above, the infrared radiation of the mK temperature zone is selectively filtered. By adjusting the proportion of different castable epoxy resin wave-absorbing materials, for example, by adjusting the mixing proportion of ECCOSORB CR-110 and stycast2850, preferably, the proportion of ECCOSORB CR-110 and stycast2850 is set to 10: 1. The ECCOSORB CR-110 is low-pass frequency (C wave band), high-frequency resistance (more than Ka wave band), stycast2850 is extremely low in insertion loss and can relieve low-temperature stress, so that the insertion loss and out-of-band suppression of the filter can be controlled, infrared radiation is effectively eliminated, and the filter is easy to produce, assemble and debug.
Furthermore, the filter cavity 3 is made of copper materials, and the structure is stable and reliable.
Further, the inner conductor 6 is made of beryllium bronze.
Further, the insulating medium plate 5 is made of polytetrafluoroethylene. The insulating dielectric sheet 5 serves as a support member for supporting the inner conductor 6 and fixing the infrared absorbing section 4.
Furthermore, the filter cavity 3 is provided with an injection hole 8 and a vent hole 7. The injection hole is used for injecting the castable epoxy resin wave-absorbing material into the filter cavity, and in the injection process, gas in the filter cavity is exhausted through the vent hole. ECCOSORB CR-110 and stycast2850 are mixed, injected into the filter cavity from the injection hole by a syringe to form an infrared absorption part, then the infrared filter is placed into a vacuum cavity, vacuumized, residual gas in the mixed gel is removed, and after standing for 24 hours, the infrared filter is placed into liquid nitrogen to ensure no damage, thus the preparation is finished.
The parasitic phonon and photon quasi-particle at low temperature come from infrared heat radiation, a common cavity filter cannot filter out the parasitic phonon and photon quasi-particle, and the castable epoxy resin wave-absorbing material (ECCOSORB CR-110) adopted by the invention can absorb the part of infrared heat radiation at low temperature. In addition, the invention can relieve low-temperature stress and adjust loss by adding stycast2850 in castable epoxy resin wave-absorbing material (ECCOSORB CR-110).
Considering that the castable epoxy resin wave-absorbing material (ECCOSORB CR-110) has extremely low loss in a C wave band and sharply increases loss in a frequency band of Ka and above; and the heat conduction epoxy resin material stycast2850 full frequency channel loss is low to can alleviate stress, consequently, through mixing the two according to certain proportion, can realize the infrared filtering characteristic under the low temperature. The low-temperature filtering characteristic of the device is realized by mixing the castable epoxy resin, for example, ECCOSORB CR-110 and stycast2850 are mixed according to the proportion of 10:1 or other proportions, the insertion loss and out-of-band inhibition of the filter can be controlled, the influence of low-temperature stress can be relieved by mixing the stycast2850 (the stress can influence the reliability of the device and can also cause frequency band offset), and the infrared radiation is effectively eliminated.
The above-mentioned embodiments are merely illustrative of the preferred embodiments of the present invention, and do not limit the scope of the present invention, and various modifications and improvements of the technical solution of the present invention by those skilled in the art should fall within the protection scope defined by the claims of the present invention without departing from the spirit of the present invention.