Gano Nisa na Quantum: Amfani da LIDAR na Boye ta Hanyar Kididdigar Zafi na Photons Masu Haɗuwa

1. Gabatarwa & Bayyani

Wannan takarda, "Gano Nisa na Quantum," ta gabatar da wani sabon tsari na Gano Hasa da Nisa (LIDAR) wanda ke amfani da ka'idojin kimiyyar haske na quantum don cimma aiki a boye. Babban sabon abu ba ya cikin wuce ma'aunin sigina zuwa amo (SNR) na gargajiya, amma a cikin amfani da wani muhimmin sifa na nau'i-nau'i na photons masu haɗuwa: rabin yanayin matsi mai nau'i biyu yana cikin yanayin zafi mai cikakkiyar gauraye. Wannan yanayin bai bambanta da kididdigar yanayin zafi na halitta na baya ba. Tsarin yana amfani da wannan photon "mai zaman kansa" a matsayin sigina mai bincike. Ga wani mai lura ko na'urar gano waje, binciken ya haɗu da amo na zafi na muhalli, yana ba da kamewa na asali. Photon "sigina" mai alaƙa ana ajiye shi a cikin gida, kuma gano shi yana nuna lokacin isowar ɗan'uwansa mai haɗuwa, yana ba da damar auna nisa daidai yayin da yake ɓoye.

2. Ra'ayoyin Tsaki & Bayanin Ka'idoji

2.1 Haske na Quantum & Iyakokinsa

Aikin ya tsaya a fagen haske na quantum. Haske na quantum na gargajiya yana nufin amfani da haɗuwa don cimma fa'ida ta gano (har zuwa 6 dB bisa ka'ida) a cikin yanayi mai asara da amo idan aka kwatanta da yanayin haɗin kai na gargajiya. Duk da haka, kamar yadda aka lura a cikin takarda kuma goyon baya daga ayyukan gaba (misali, Shapiro & Lloyd, 2009; Zhuang et al., 2017), wannan fa'idar tana da iyaka kuma sau da yawa ana soke ta a cikin yanayi na zahiri ta hanyar fitattun maɓuɓɓuka na gargajiya. Marubutan sun yi hujja daidai cewa ga LIDAR, babban dalilin amfani da yanayin quantum ya canza daga ribar SNR ɗaya zuwa boye da ƙarancin yuwuwar kama (LPI).

2.2 Fa'idar Yanayin Zafi

Mahimmin fahimta shine kididdigar photon na zafi na nau'i ɗaya daga cikin yanayin ɓacin rai mai nau'i biyu (TMSV), wanda aka samar ta hanyar Juyawa ta Parametric ta Kwatsam (SPDC). Ma'aunin yawa da aka rage don nau'i ɗaya shine: $$\hat{\rho}_{\text{zafi}} = \sum_{n=0}^{\infty} \frac{\bar{n}^n}{(\bar{n}+1)^{n+1}} |n\rangle\langle n|$$ inda $\bar{n} = \sinh^2 r$ shine adadin photon na matsakaita kuma $r$ shine ma'aunin matsi. Wannan yayi daidai da yanayin radiation na blackbody a cikin nau'i ɗaya. Wannan sifa, wanda sau da yawa ake ɗauka a matsayin abin da ke iyakance tsafta, ana sake amfani da shi azaman kadari don ɓoyewa.

3. Tsarin Gano Nisa na Quantum

3.1 Bayanin Tsarin

Maɓuɓɓuka: Maɓuɓɓukan SPDC mai nau'i-nau'i na bakan haske yana samar da nau'i-nau'i na photons sigina-mai zaman kansa masu haɗuwa.
Watsa Bincike: Ana aika katakon mai zaman kansa (yanayin zafi) zuwa ga wani abin da zai iya zama hari.
Sanarwa & Tsara Lokaci: Ana karkatar da katakon sigina zuwa na'urar gano cikin gida mai inganci. Abin da aka gano yana sanar da fitar da ɗan'uwansa mai zaman kansa kuma yana fara agogo mai daidaito.
Gano Tunani: Ana tattara kowane photon da ke dawowa daga yankin abin hari. Saboda asara mai tsanani, wannan yawanci sigina ne na matakin photon ɗaya.
Haɗin Kai & Gano Nisa: Da'irar haɗin kai tana danganta abin da ya faru na sanarwa na gida tare da gano photon dawowa. Jinkirin lokaci yana ba da nisan abin hari: $d = c\Delta t / 2$.

Boyewar ya samo asali ne daga gaskiyar cewa katakon mai zaman kansa na waje yayi daidai da baya a bakan haske da kididdiga, yana mai da shi ba ya faɗakarwa.

3.2 Tsarin Lissafi Mai Muhimmanci

Ana nazarin aikin tsarin ta hanyar yuwuwar gano yanayin. Idan aka ba da sanarwa a lokacin $t_0$, yuwuwar gano photon dawowa a lokacin $t_0 + \tau$ yana ƙaruwa ta hanyar alaƙar quantum, ko da yake nau'ikan ɗaiɗaikun suna cikin zafi. An samo ma'aunin sigina zuwa amo don gano abin hari a kan kwararar baya $\Phi_B$, yana nuna juriya saboda baya ba shi da alaƙa da sanarwa, yayin da sigina na gaskiya yana da alaƙa.

4. Nazarin Fasaha & Sakamako

4.1 Tsarin Gwaji & Hanyoyin Aiki

Duk da yake takardar ta fi zama ta ka'ida, tana nuna tsarin gwaji bisa ga ka'idar haske na quantum na yau da kullun: laser mai bugun jini yana buga kristal mara layi (misali, PPKTP) don SPDC, madubai masu ban sha'awa don raba sassan sigina da na mai zaman kansa, na'urori masu gano photon guda ɗaya na wayoyi masu iya aiki da sanyaya (SNSPDs) don gano inganci, da kuma tsarin ƙididdige photon guda ɗaya mai haɗin lokaci mai sauri (TCSPC) don nazarin haɗin kai. Ma'auni mai mahimmanci shine ma'aunin haɗin kai zuwa na bazata (CAR), wanda dole ne ya yi girma don bambanta tunani na gaskiya na abin hari daga ƙididdiga na bazata da baya ko ƙididdiga na duhu suka haifar.

4.2 Sakamako & Ma'aunin Aiki

Babban sakamakon takardar shine nazarin kwatancen da ke nuna cewa duk da yake bugun jini mai haske na gargajiya ($\sim10^6$ photons/bugu) koyaushe zai haifar da mafi kyawun yuwuwar gano ɗaya a cikin yanayi mai matsakaici, tsarin quantum yana aiki a cikin yanayi daban-daban na asali. Aikinsa yana siffanta shi da:

Ƙarancin Yuwuwar Kama (LPI): Kididdigar photon na katakon bincike ta yi daidai da baya, yana mai da ganinsa ta hanyar abokin gaba mai warware bakan haske ba zai yiwu ba.
Dakatar da Baya: Haɗin kai na sanarwa-mai zaman kansa yana ba da tsarin tacewa na ɗan lokaci, yana ƙi photons waɗanda ba su da alaƙa da sanarwa, don haka yana dakatar da hasken baya mara alaƙa.
Aiki a Iyakar Quantum: Tsarin yana aiki yadda ya kamata a matakin photon ɗaya ko ƴan kaɗan a kowane yanayi na ɗan lokaci, wanda shine iyakar haske na ainihin maɓuɓɓukan SPDC masu amfani.

Ana ƙididdige aikin dangane da adadin lokutan ma'auni da ake buƙata don cimma wani tabbacin gano gano da LIDAR mai bugun jini na gargajiya, yana nuna ma'ana mai juyawa inda boyewar tsarin quantum ya zama fa'ida mai mahimmanci.

5. Nazari Mai Zurfi & Fassarar Kwararru

Fahimta ta Tsaki: Frick da sauransu sun aiwatar da juyawa mai hikima. Sun daina ƙoƙarin cin nasara a yaƙin SNR da ba za a iya cin nasara ba a kan laser na gargajiya na megawatt kuma a maimakon haka sun karɓi "rauni" na quantum - yanayin zafi na tsarin TMSV - a matsayin makamin ɓoyewa na ƙarshe. Wannan ba haske na quantum ba ne don mafi kyawun gano; haske ne na quantum don ganon da ba za a iya musantawa ba.

Kwararar Ma'ana: Hujjar tana da kaifi sosai: 1) Riba da aka yi alkawarin haɗuwa an iyakance su a 6dB kuma sau da yawa ba su da amfani a aikace. 2) Duk da haka, kididdigar zafi na rabin nau'i-nau'i gaskiya ce ta zahiri. 3) Don haka, idan manufar ita ce guje wa ganin yayin gano, wannan "aibi" ya zama siffa. Tsarin yana biye da wannan farkon a hankali, ta amfani da sanarwa don cire bayanan lokaci daga binciken da aka ɓoye.

Ƙarfi & Aibobi: Ƙarfi: Babban ra'ayin yana da sauƙi kuma yana dogara ne akan tushen ka'idodin haske na quantum. Yana magance ainihin buƙatar soja/tsaro (ganowa a boye) wanda fa'idodin SNR ɗaya ba su yi ba. Yana sanya nagarta daga larura (ƙarancin haske na maɓuɓɓuka). Aibobi: Giwa a cikin ɗaki shine haɓakawa na aikace-aikace da ƙimar. Kamar yadda marubutan suka yarda, maɓuɓɓukan SPDC suna da duhu. Cimma ɗaukar yanki mai ma'ana ko saurin bincike da binciken matakin photon ɗaya ƙalubale ne na injiniya. Tsarin kuma yana ɗauka cewa abokin gaba yana yin gano bakan haske kawai. Bincike mai aiki ko ƙarin nazarin yanayin quantum na iya bayyana sigina. Nazarin, duk da yana da inganci, yana da ɗan tsattsauran ra'ayi kuma bai cika fuskantar tashin hankali na yanayi mai tsanani ko sifofin abin hari masu rikitarwa ba.

Fahimta Mai Aiki: Ga masu bincike: Ƙimar takardar tana cikin ayyana sabon yanki na aikace-aikace. Matakan gaba ba kawai maɓuɓɓukan SPDC masu haske ba ne, amma tsarin gauraye. Shin mutum zai iya amfani da binciken quantum mai ƙarancin haske don ɗaukar abin hari a boye/ kulle, sannan a biye da ɗan gajeren bugun jini na gargajiya mai ƙarfi don cikakken hoto? Ga masu ba da kuɗi da manajoji na shirye-shirye: Wannan aikin yana ba da hujjar ci gaba da saka hannun jari a cikin haɗin gwiwar hoto na quantum da na'urori masu gano inganci ba don "fa'ida" na quantum na gabaɗaya ba, amma don takamaiman iyawa na ɓoyewa masu mahimmanci na aiki inda tsarin gargajiya ke da matsala ta sa hannu na asali. Yana canza ma'auni daga "doke SNR na gargajiya" zuwa "cimma iyakokin ganowa na musamman na aiki."

Wannan aikin yana haɗuwa da manyan abubuwan da ke faruwa a cikin fahimtar quantum, kamar amfani da yanayin matsi don gano igiyar nauyi (LIGO) ko cibiyoyin NV don ma'aunin maganadisu, inda kaddarorin quantum ke ba da damar auna ma'auni a cikin yanayin da binciken gargajiya ba zai iya kaiwa ba. Hakazalika, a nan, sifa ta quantum (haɗin kai da aka sanar daga binciken yanayin zafi) tana ba da damar aiki a cikin yanayin ɓoyewa wanda duk wani maɓuɓɓuka na gargajiya mai haske ba zai iya kaiwa ba, ba tare da la'akari da ƙarfinsa ba.

6. Tsarin Nazari & Misalin Lamari

Yanayi: Sa ido a boye a cikin teku. Jirgi maras matuki ko tauraron dan adam yana buƙatar tantance nisa zuwa jirgin ruwa a cikin buɗaɗɗen teku ba tare da bayyana kasancewarsa ba. Baya shine hasken rana da hasken sama.

Aiwatar da Tsarin:

Ayyana Samfurin Barazana: Jirgin ruwa na abokin gaba yana da na'urori masu aiki da lantarki/hoto na infrared (EO/IR) masu sa ido kan bugun jini na laser.
Ma'auni na Tsarin:
- Maɓuɓɓuka na Quantum: SPDC na 1550 nm (mai kare ido, ƙarancin asarar yanayi), $\bar{n} = 0.1$ photons/mode, nau'ikan bakan haske 100, maimaita ƙimar 10 MHz.
- Ma'auni na Gargajiya: Laser mai bugun jini, 1550 nm, 1 µJ/bugu ($\sim 7.8\times10^{11}$ photons/bugu), irin wannan maimaita ƙimar.
- Haɗin kai: Nisan kilomita 10, asarar yanayi mai hanyar ɗaya 30 dB, $10^{-9}$ photon na baya a kowane nau'i a kowane bugun jini.
Nazari:
- Gargajiya: Babban yuwuwar ganowa ta abokin gaba saboda bugun jini mai haske, mai haɗin kai. Babban yuwuwar dawowa ɗaya.
- Quantum: Katakon waje bai bambanta da $\bar{n}=0.1$ zafi na baya ba. Yuwuwar abokin gaba na bambanta shi da baya na halitta kusan sifili ne. Yuwuwar dawowa ɗaya ƙanƙanta ce ($\sim 10^{-10}$), tana buƙatar haɗawa sama da dubunnan bugun jini. Duk da haka, ma'anar haɗin kai tana tace kusan duk baya yayin haɗawa.
Sakamako: Tsarin gargajiya yana samun nisa nan da nan amma yana faɗakar da abin hari. Tsarin quantum, bayan ƴan dakiku na haɗawa, yana samun nisa tare da babban tabbaci yayin da yake ɓoye - fa'ida mai mahimmanci ta dabara.

Wannan misalin yana nuna ciniki: ƙimar da ƙarfin ɗaya don ɓoyewa.

7. Aikace-aikacen Gaba & Hanyoyin Bincike

Haɗaɗɗun Da'irori na Hoto na Quantum: Ƙananan dukan maɓuɓɓuka (laser ɗin famfo, igiyar ruwa mara layi, masu tacewa) a kan guntu yana da mahimmanci don turawa akan ƙananan dandamali kamar jirage marasa matuki. Bincike daga cibiyoyi kamar MIT, Bristol, da Purdue a cikin igiyoyin ruwa na silicon nitride ko lithium niobate yana da alaƙa kai tsaye.
Injiniyan Bakan Haske-Lokaci: Amfani da tsefe na mitar quantum ko bugun jini na famfo da aka ƙera don yada photons masu haɗuwa a cikin ƙarin nau'ikan bakan haske-lokaci, ƙara yawan kwararar bincike yayin da ake kiyaye kididdigar zafi a kowane nau'i.
Fahimtar Gauraye Quantum-Gargajiya: Kamar yadda aka ba da shawara a cikin nazarin, amfani da tashar quantum don sa ido a shiru, ƙarancin ƙimar bayanai (ganowa, gano nisa) da kuma nuna tsarin hoto na gargajiya don ɗan gajeren lokaci, ayyuka masu ƙayyadaddun bayanai.
Giciye na Radar na Quantum (QRCS): Bincika ko haɗin kai na quantum yana ba da bayanai game da kayan abin hari ko siffa fiye da sauƙi na nisa, ƙarƙashin tsarin ɓoyewa.
Tashoshi na Yanayi & Ƙarƙashin Ruwa: Cikakken tabbacin gwaji a cikin tashoshi na zahiri masu asara da tashin hankali shine mataki na gaba mai mahimmanci don canzawa daga ka'ida zuwa fasahar filin.

8. Nassoshi

S. Lloyd, "Ƙara hankali na gano hoto ta hanyar haske na quantum," Kimiyya, vol. 321, no. 5895, pp. 1463–1465, 2008.
S.-H. Tan et al., "Haske na quantum tare da jihohin Gaussian," Phys. Rev. Lett., vol. 101, no. 25, p. 253601, 2008.
J. H. Shapiro, "Labarin haske na quantum," IEEE Aerospace and Electronic Systems Magazine, vol. 35, no. 4, pp. 8–20, 2020. (Muhimmin bita da ke bayyana iyakar 6 dB da ƙalubalen aikace-aikace).
Z. Zhang et al., "Fa'idar haɗuwa ta tsira daga tashoshi mai tsananin amo," Nature Communications, vol. 9, no. 1, p. 3812, 2018. (Nunin gwaji na haske na quantum a cikin babban amo).
Q. Zhuang, Z. Zhang, da J. H. Shapiro, "Mafi kyawun bambance-bambancen yanayi gauraye don ƙara hankali na haɗuwa," Phys. Rev. Lett., vol. 118, no. 4, p. 040801, 2017.
J. L. O'Brien, A. Furusawa, da J. Vučković, "Fasahar hoto na quantum," Nature Photonics, vol. 3, no. 12, pp. 687–695, 2009. (Mahallin haɗin gwiwar hoto na quantum).
D. G. England, B. Balaji, da B. J. Sussman, "Ƙara gano tsayawa ta amfani da nau'i-nau'i na photons masu alaƙa," Phys. Rev. A, vol. 99, no. 2, p. 023828, 2019. (Aikin gwaji mai alaƙa akan gano abin hari).
M. G. Raymer da K. Banaszek, "Injiniyan yanayin quantum da sarrafa bayanai ta hanyar tsangwama na quantum na nau'i-nau'i na photons," a cikin Sarrafa Bayanai na Quantum, Wiley, 2004. (Bayanin jihohin TMSV da kaddarorinsu).