The Euro­pean Union is pro­vi­ding 4.3 mil­lion euros in fun­ding for a new pro­ject to rese­arch high-secu­rity quan­tum com­mu­ni­ca­tion via satel­li­tes. In the QUDICE pro­ject, an inter­na­tio­nal team of rese­ar­chers, inclu­ding mem­bers of the Fraun­ho­fer Insti­tute for Applied Optics and Pre­cis­ion Engi­nee­ring IOF, aims to deve­lop com­pon­ents for space-based dis­tri­bu­tion of quan­tum keys. The new hard­ware is expec­ted to become one day the basis of a Euro­pean satel­lite net­work. At Fraun­ho­fer IOF, a minia­tu­ri­zed source for gene­ra­ting ent­an­gled light par­tic­les in the tele­com­mu­ni­ca­ti­ons wave­length range will be built spe­ci­fi­cally for this pur­pose. The pro­ject has recently star­ted its three-year term.

Using ent­an­gled light par­tic­les to com­mu­ni­cate in Europe in a prac­ti­cally tap-proof man­ner – a goal towards which an inter­na­tio­nal team of EU rese­ar­chers is working. Within the new QUDICE pro­ject, they want to deve­lop tog­e­ther com­pon­ents and sys­tems for space-based quan­tum key dis­tri­bu­tion. In this way, QUDICE wants to make a signi­fi­cant con­tri­bu­tion to one day being able to rea­lize a Euro­pean net­work of satel­li­tes for quan­tum-based com­mu­ni­ca­tion. Such a net­work will spe­ci­fi­cally pro­tect the pri­vacy of Euro­pean insti­tu­ti­ons, com­pa­nies, and citi­zens, while streng­thening Europe’s inde­pen­dence from cri­ti­cal (quan­tum) tech­no­lo­gies from abroad.

Com­pact and highly effi­ci­ent pho­ton pair source for use in space

Within the frame­work of QUDICE, a minia­tu­ri­zed, space-qua­li­fied pola­riza­tion-ent­an­gled pho­ton pair source (EPS) in the tele­com­mu­ni­ca­ti­ons wave­length range will be built at the Fraun­ho­fer IOF in Jena. This source will later be inte­gra­ted into a satel­lite. The pho­ton pair source must the­r­e­fore meet spe­cial requi­re­ments for use in space: For exam­ple, it must be par­ti­cu­larly small and com­pact. The aim is to achieve a size simi­lar to that of a one liter milk carton.

The rese­ar­chers at Fraun­ho­fer IOF must the­r­e­fore minia­tu­rize all the indi­vi­dual com­pon­ents of the source and inte­grate them on seve­ral chips. Fur­ther­more, the source must be able to with­stand strong vibra­ti­ons as well as large tem­pe­ra­ture fluc­tua­tions, which occur during the launch of the satel­lite on its way into space. The pho­ton pair source will the­r­e­fore be based on recent advan­ces in non­linear optics and engi­nee­ring. The goal for the new source is to achieve 10^9 pairs of ent­an­gled light par­tic­les per second and a bit rate that exceeds the cur­rent state of the art by seve­ral orders of magnitude.

Fraun­ho­fer IOF will work clo­sely with the Insti­tute of Pho­to­nic Sci­en­ces (ICFO) from Spain – one of twelve part­ners in the QUDICE pro­ject – to con­s­truct the pho­ton pair source in space-qua­li­fied qua­lity. Tog­e­ther, the insti­tu­tes will deve­lop a novel design for the ent­an­gled pho­ton source, which will allow the inte­gra­tion of the com­pon­ents and thus a par­ti­cu­larly com­pact setup. To this end, ICFO will design spe­ci­fic sub­sys­tems for each cho­sen QKD imple­men­ta­tion, while Fraun­ho­fer IOF will imple­ment them. Sub­se­quently, the Fraun­ho­fer Insti­tute in Jena will cha­rac­te­rize all opto-elec­tro­nic com­pon­ents, while ICFO will per­form the QKD implementations.

Streng­thening Europe’s tech­no­lo­gi­cal sove­reig­nty in quan­tum technologies

Alre­ady in 2019, an agree­ment bet­ween the EU Com­mis­sion and the Euro­pean Space Agency (ESA) took the first step towards the deve­lo­p­ment of a highly secure pan-Euro­pean infra­struc­ture for increased data secu­rity. Quan­tum key dis­tri­bu­tion repres­ents a cru­cial enab­ling tech­no­logy in this regard. QUDICE is inten­ded to drive for­ward the cor­re­spon­ding rese­arch and deve­lo­p­ment work. The pro­ject is the­r­e­fore being fun­ded by the Euro­pean Union within the frame­work of the »Hori­zon Europe« pro­gram with 4.3 mil­lion euros. 450,000 euros of this will flow into the work at Fraun­ho­fer IOF in Jena.

The rea­liza­tion of the pro­ject goal requi­res exper­tise from a wide range of fields – from quan­tum phy­sics, mecha­ni­cal engi­nee­ring, and opti­cal engi­nee­ring to radio com­mu­ni­ca­ti­ons, satel­lite tech­no­logy, and space tech­no­logy. Through the col­la­bo­ra­tion of world-lea­ding rese­arch insti­tu­ti­ons as well as tech­no­logy deve­lo­pers and manu­fac­tu­r­ers, but also sys­tem inte­gra­tors, an inter­di­sci­pli­nary con­sor­tium is for­med in which lea­ding experts from their respec­tive fields are gathered.

In addi­tion to the Fraun­ho­fer IOF, the part­ners of the QUDICE pro­ject are: Uni­ver­sity of Padova, Think­Quan­tum SRL, Stel­lar Pro­ject SRL, Argo­tec, Tha­les Ale­nia Space (all Italy), The Insti­tute of Pho­to­nic Sci­en­ces ICFO, Quside SL, Sate­liot IOT Ser­vices SL (all Spain), Centre Natio­nal de la Recher­che Sci­en­ti­fi­que, Sor­bonne Uni­ver­sité (all France), L‑Università ta‹ Malta (Malta).

Rese­ar­chers at Fraun­ho­fer IOF have repea­tedly demons­tra­ted the exch­ange of quan­tum keys over dif­fe­rent paths and distances, e.g., using free beams within a city or via opti­cal fibers laid in the ground bet­ween dif­fe­rent metro­po­li­tan regi­ons. Howe­ver, quan­tum key exch­ange via satel­lite also enables con­nec­ti­vity to areas where fiber con­nec­ti­vity is not pos­si­ble or limi­ted, e.g., off­shore. Fur­ther­more, space-based quan­tum key exch­ange pro­vi­des a true backup in the event of a natu­ral dis­as­ter that would des­troy fiber-based infra­struc­tures, or a wide­spread net­work outage.