Superconducting Nanowire Single- Photon Detection System

Transcription

1 TM Superconductng Nanowre Sngle- Photon Detecton System Installaton and Operaton Manual January 26, 2017 Quantum Opus, LLC Helm Street Plymouth, MI USA

2 General Informaton Warranty Ths Quantum Opus product s warranted aganst defects n materals and workmanshp for a perod of one (1) year from the date of shpment. Servce For warranty servce or repar, ths product must be returned to a Quantum Opus authorzed servce faclty. Some components may be servceable drectly from the suppler. Contact Quantum Opus before returnng ths product for repar. Proper Use All Quantum Opus products are ntended for use by properly traned users. In no event shall Quantum Opus be lable for any drect, ndrect, puntve, ncdental, specal consequental damages, to property or lfe, whatsoever arsng out of or connected wth the use or msuse of our products. Contact Informaton Quantum Opus, LLC Helm Street Plymouth, MI Telephone (269) Emal: nfo@quantumopus.com Webste: Document Informaton Ths document s provded by the copyrght holders as s and any express or mpled warrantes, ncludng, but not lmted to, the mpled warrantes of merchantablty and ftness for a partcular purpose are dsclamed. In no event shall the copyrght holder be lable for any drect, ndrect, ncdental, specal, exemplary, or consequental damages (ncludng, but not lmted to, procurement of substtute goods or servces; loss of use, data, or profts; or busness nterrupton) however caused and on any theory of lablty, whether n contract, strct lablty, or tort (ncludng neglgence or otherwse) arsng n any way out of the use of ths document, even f advsed of the possblty of such damage. Copyrght c Quantum Opus, LLC, All rghts reserved. 2

3 Safety Notces A notce dentfes a hazard. Ths type of notce dentfes a procedure, practce, or smlar, that, f not properly performed or adhered to, could result n damage (possbly sgnfcant) to persons or property. Do not proceed past a notce untl the ndcated condtons are fully understood and met. If there s any queston about proper performance of the procedure or practce, contact Quantum Opus support for gudance. NOTE A NOTE notce dentfes a procedure, practce, or smlar that f not properly performed or adhered to, could result n degraded system performance, reduced system up-tme, or ncreased frequency of system mantenance. Although adherence to a NOTE s not safety crtcal, adherence s requred to ensure system performance meets specfcatons. If there s any queston about proper performance of the procedure or practce, contact Quantum Opus support for gudance. 3

4 Fgure 1: Photo of a typcal four-channel Opus Oneunt contanng four superconductng nanowres, cryogenc vacuum system, and fber optc couplers. Varous confguratons are avalable wth up to 16 detector channels n the above 19-nch rack confguraton (3U heght). Specfc optons and confguratons may vary. 4

5 1 Introducton The Opus Ones a hgh-speed, hgh-effcency, fber-coupled, sngle-photon detecton system usng superconductng nanowre technology. The system can contan between one and sxteen nanowre detectors, dependng on confguraton. 1.1 Overvew Electroncs Unt Power GPIB SRSNSIM900 SIM922 module QOQAMPQSIM modulebs/ 1 2 vnvnv n 1 2vNvNv n vnvnv NanowreNpulsesNout BSMA/ Thermometer CableNDB9NM/F vnvnv NanowreNcableBs/ SMANMQMNDoubleQShelded Opus One Unt OpusNOne 1 2 vnvnv n 1 2vNvNv n vnvnv LghtNn BFber/ ColdNhead drvencable PressurzedNhelum compressornlnes Compressor Unt Power Compressor CoolngNwaterN Fgure 2: Nanowre system schematc showng Opus Onehead unt, electroncs unt, and compressor wth all connectons. The nanowre system has three man physcal components, as dentfed n Fgure 2: 1. The Electroncs Unt that provdes system thermometry and nanowre devce con- 5

6 trol and montorng. 2. The Opus One Unt consstng of the vacuum and cryogenc components, nanowre detectors, and nanowre optcal and electrcal connectons. 3. The Compressor Unt that provdes the hgh-pressure, hgh-purty helum and valve control sgnals to obtan and mantan the low temperatures requred for superconductng nanowre operaton. 6

7 2 Installaton Ths secton covers unpackng and nstallng your new nanowre detector system. Several system components contan hgh-pressure helum gas. Follow manufacturer recommendatons for nstallaton. Eye protecton s recommended durng nstallaton. Follow local regulatons and recommendatons for proper personal protectve equpment (PPE) when workng wth hgh pressure gases. Ensure the system has been powered off for 24 hours before openng the vent valve or makng changes to the hgh-pressure connectons between the detector head and the compressor. 2.1 Preparaton for Installaton Before unpackng your Opus One system head, the compressor must be nstalled. Carefully consder the placement of the compressor and Opus One head unt. For ths dscusson, refer Fgure 2 on page 5. It s normal for the hgh-pressure helum lnes to move slghtly durng system operaton. Ensure the lnes do not rub on sharp corners or on other objects that may become damaged from abrason wth the metal tubng such as electrcal wrng or water lnes. NOTE Dstances over 3m between the detector head and compressor may reduce detector performance because of decreased system coolng power. 1. Determne compressor and hgh-pressure helum locaton approprate for proper proxmty to your water and power connectons. NOTE Because of the polarzaton senstvty of the nanowre devces, t s mportant to mnmze uncontrolled polarzaton drft between your source and 7

8 the detector unt. Polarzaton drft can be made worse wth long optcal fbers, fbers that contnually change poston (e.g., due to vbraton or ar currents), or fbers that change temperature. 2. Determne the Opus One unt locaton approprate for your source of photons, ensurng that the pressurzed hgh-purty helum lnes wll move freely and wll not be under tenson. Mnmze the dstance between your optcal source and the detector unt. 3. Determne the best locaton for the electroncs unt (SIM900 plus assocated modules), notng that t s ntended to be operated ether drectly above or below the Opus One detector head to mnmze the ntroducton of nose between the electroncs and the Opus One unt. 2.2 Compressor Unt Installaton As per manufacturer recommendatons, nspect all gaskets and o-rng surfaces to ensure they are present, undamaged, and clean. A mssng or damaged o-rng could result n rapd, catastrophc release of hgh-pressure helum. Do not use any lubrcants on the connectors. Always ensure connectors are mated properly to avod any loss of hgh-purty helum. Do not nstall the helum lnes to the detector head untl nstructed to do so n the order gven below. Installaton of the helum lnes n the wrong order, or to the wrong ports, may requre factory repar of the Opus One unt. 1. Establsh the proper electrcal and water connectons to the compressor accordng to documentaton provded separately by the compressor manufacturer. Be sure to comply wth all manufacturer recommendatons and local laws, codes, and buldng recommendatons. 2. Perform any recommended compressor run testng. See provded compressor manufacturer documentaton. 3. After any requred compressor run testng, nstall the hgh-pressure helum lnes onto the compressor SUPPLY and RETURN connectons, as descrbed n the compressor manufacturer documentaton. 8

9 2.3 Opus One Unt Installaton Do not lft or poston the detector head by puttng force on the front panel connectors or on the rear valve, port, hgh-pressure tubng connectons, or wrng connectors. Do not rest the unt, even temporarly, on ts front (.e., on the electrcal and optcal connectons) or rear (.e., on the valve, port, hgh-pressure tubng connectons). Do not attempt to mount the detector head nto a rack enclosure wthout both support from both front and back ral flanges. Damage to the system s lkely. Refer to the dagram of the Opus One unt shown n Fgure 3 on the next page for the procedures n ths secton. 1. Determne how to properly lft the detector head. Avod lftng by any valve, port, electrcal, or tubng connectons. As long as you avod the tubng lnes, you may lft by the central sold alumnum block at the rear of the unt, as shown n Fgure 3 on the next page. 2. Carefully remove the Opus One unt from ts packagng. Note that the unt has a sgnfcant fracton of ts weght toward the back. 3. Remove any protectve wrappng around the Opus One unt and on the front panel. 4. For rack-mount operaton, contact Quantum Opus support for gudance on the selecton of an approprate shelf mount. 5. If desred, apply the provded adhesve feet near the corners of the bottom panel of the detector head. The head may be set temporarly on ts top, bottom, rght or left sdes to facltate applyng the feet. 6. Temporarly place the Opus One unt n a locaton near ts operaton locaton so that, after the hgh-pressure helum lnes are connected, t can be postoned nto ts fnal nstalled locaton wth mnmal stran on the hgh-pressure helum connectons at the rear of the unt. 7. The pressurzed helum lnes must be connected n the followng order. 9

10 Fgure 3: Rear vew of the Opus One detector unt showng a suggested lft pont for nstallaton. a) Ensure the SUPPLY and RETURN lnes are already connected to the compressor and properly labeled SUPPLY and RETURN. b) If (optonal) pressurzed rght-angle adapters are to be used, contact Quantum Opus for the proper nstallaton procedure. Usng the mproper method of connectng the helum lnes, connectng n the mproper order, or erroneously nterchangng the RETURN and SUPPLY lnes may result n permanent damage to the tubng lnes or necesstate servce to the Opus One unt. Adhere to the followng procedures carefully. c) Frst, usng the proper three-wrench procedure as descrbed n the Sumtomo SRDK Operatons Manual (provded by Quantum Opus, upon request), connect 10

11 the RETURN hgh-pressure helum lne to the RETURN connector on the rear of the Opus One unt. d) Second, agan usng the proper three-wrench procedure, connect the SUP- PLY hgh-pressure helum lne to the SUPPLY connector on the read of the Opus One unt. e) Connect the provded electrcal drve cable between the compressor and the Opus One unt. 11

12 3 Electroncs Unt Installaton The Opus One devces and electroncs are senstve to Electrostatc Dscharge (ESD). Ensure you are properly grounded before changng cable connectons of any type. Ensure that the QO-AMP-SIM modules are powered on and the STATUS lght s llumnated green ( ) when connectng the SMA cables between the QO-AMP-SIM module and the Opus One. Do not overtghten the SMA or optcal connectors. Fnger-tght connectons are recommended for fber connectons. Slghtly tghter than fnger-tght connectons are recommended for SMA connectons. Overtghtenng the connectors may loosen the nternal connectors n the Opus One unt or cause damage to the connectors, damage to cables, or ncreased system losses and nose. NOTE Use only the provded double-shelded SMA cables between the Opus One unt and the QO-AMP-SIM modules to reduce the possblty of ncreased electrcally nduced nose counts. 1. Dependng on the optons purchased wth your system, varous Stanford Research Systems SIM-compatble modules (ncludng QO-AMP-SIM modules) have been provded wth your system. Wth the SIM900 power off, nsert all desred modules frmly nto the SIM900 rack, as per documentaton on the SIM900 rack avalable from Stanford Research Systems at Note that, f nstallng fewer than eght QO-AMP-SIM modules, t s typcally most convenent to place the QO-AMP-SIM modules n the farthest rght (hghest numbered) slots to keep the SMA connectons close to the Opus One unt SMA connectors. 2. If seven or fewer QO-AMP-SIM modules are to be used, nstall the provded SIM922 Dode Temperature Montor nto an unused slot n the SIM900 rack. If eght or more QO-AMP-SIM modules are to be used, attach the provded 15-pn (DB15 male to DB15 female) extenson cable between the rear of the SIM922 module and the rear DB15 connector labeled Remote SIM (Port 9) on the SIM900 rack unt. 3. Attach the provded 9-pn (DB9 male to DB9 female) flter adapter to the upper DB9 connector on the back of the SIM922 Dode Temperature Montor. 4. Attach the provded 9-pn cable between the flter and the Therm connector on 12

13 the rear of the Opus One unt. 5. Power on the SIM900 rack and ensure that the SIM922 module reads a voltage of approxmately 0.6 Volts on both channel 1 and channel 2 thermometers. You may need to press the small Unts button at the bottom of the SIM922 front panel to swtch to V from K to see the thermometer voltages. 6. At ths tme all QO-AMP-SIM modules should have ther STATUS lght llumnated green ( ). The green status lght ndcates a safe, standby mode for connectng and dsconnectng the Opus One unt SMA cables. 7. Wth the SIM900 unt stll powered and the QO-AMP-SIM status lghts green, connect the Opus One to the QO-AMP-SIM modules usng the provded 12-nch doubleshelded SMA cables. For each detector, connect one cable from the Electrcal SMA connector on the Opus One unt to the NW nput on a correspondng QO- AMP-SIM module n the SIM900 rack. Tghten the SMA connectors slghtly tghter than fnger tght usng a small SMA wrench (desred torque should be 0.3 to 0.6 N m, 3 to 5 n lbs). 8. Once all QO-AMP-SIM modules are connected to ther respectve nanowre connectors, the SIM900 rack may be powered down. All connectons may be left n place when powerng up and power down the SIM

14 4 System Operaton Ths chapter detals the Cool down and Warm up procedures for the cryogenc components of the Opus One nanowre system. If ether the compressor or Opus One unt operate n a seemngly erratc or unsafe manner, turn off the power to the compressor and the electroncs unt and contact Quantum Opus for addtonal help. Whenever usng a vacuum pump to evacuate a system, ensure there s adequate slack n the pumpng lne to allow for lne contracton (sometmes very sgnfcant) durng pumpng. Inadequate lne length can cause unsafe forces on the pump, pumpng lnes, or Opus One unt and can cause equpment to be damaged or to move n undesred ways (e.g., tp over, fall off of shelvng). 4.1 Cool Down Procedure The procedures n ths chapter should be accomplshed for frst-tme operaton and repeated any tme that the system has been allowed to warm above approxmately 45 Kelvn, for example n case of accdental power falure, coolng water loss, or ntentonal system shutdown. NOTE The system should be n ts warm state before startng ths procedure to ensure proper cool down. A warm state s ndcated on the SIM922 Dode Temperature Montor SIM module by both channel 1 and channel 2 thermometers readng above 280 K. Ths state should be acheved wthn 24 hours after the system has been powered off. For the system warm-up procedure, see Secton 4.2 on page 16. NOTE A vacuum pump that reaches a pressure below approxmately 1 mbar (0.75 Torr) s requred for the cool down procedure, but s not requred for contnuous operaton. A dry, or ol-free, pump s preferred to prevent the possblty of ol backstreamng that could contamnate the cryogenc system. 14

15 When closng the green vacuum valve (labeled Valve ) on the rear of the Opus One unt, do not overtghten. Ths valve should be close only untl fnger tght. Never use plers or tools to close the valve. Usng excessve force to close the valve can permanently damage the valve mechansm. The cool down procedure steps should be completed n the followng order: 1. Evacuate the Opus One unt accordng to the followng procedure. a) Ensure the green vacuum valve (labeled Valve ) on the rear of the Opus One unt s closed by gently applyng clockwse torque. The valve should not turn under lght torque. Do not overtghten. b) Remove the NW25 cap and o-rng from the vacuum port (labeled Pump/Vent ) loosenng the clamp screw and removng the clamp. c) Inspect the o-rng to ensure t s dust-free and has no cracks or flaws. If so, replace the o-rng before proceedng. d) Usng the o-rng and clamp, connect the vacuum pump va an approprate NW25 vacuum tube (not provded) to the vacuum port and tghten the clamp securely. e) Follow the vacuum pump manufacturer s recommended procedure for startng the pump and evacuatng the pump tube. f) Slowly open the vacuum valve on the Opus One unt. The valve s fully open once rotated counterclockwse approxmately two (2) full turns. 2. Ensure the compressor s ready for use, ncludng turnng on any requred coolng water or electrcal breakers. 3. Turn on the electrcal power to the compressor. The hum of the compressor and the approxmately 1 cycle-per-second hss of the Opus One unt should begn mmedately. If the 1 cycle-per-second sound from the Opus One s not heard, turn off the compressor and confrm that the helum lne and electrcal connectons between the Opus One unt and the compressor are correct, as per Secton Confrm that the temperature readng of the channel 1 thermometer on the SIM922 Dode Temperature Montor ndcates the temperature has begun to decrease. 5. Wat untl the temperature of the channel 1 thermometer drops below approxmately 50 K, then close the vent valve by turnng the green valve knob clockwse untl fnger tght. NOTE If usng a dry pump wth strong pumpng capabltes such as a turbomolecular drag pump (.e., turbo pump), you may choose to wat untl 15

16 the system s fully cold to close the green vacuum valve as there s low rsk of backstreamng contamnants such as ar or pump ol nto the cryogenc space of the Opus One unt. 6. Once the vacuum valve s closed you may dsconnect the pumpng lne and turn off the pump, accordng to the process recommended by the pump manufacturer. 7. Seal the NW25 Pump/Ventport usng the NW25 o-rng, cap, and clamp. 8. Wat untl the temperature of the channel 2 thermometer (on the SIM922 Dode Temperature Montor) ndcates the system s at s base temperature (typcally below 2.7 K). The cool-down takes approxmately three (3) hours from the tme the compressor s turned on. 9. The Opus One devces are now ready to be used. Refer to Secton Warm Up Procedure Ensure the system has been turned off for a mnmum of 24 hours before openng the vent valve or makng changes to any of the hgh-pressure helum lne connectons. Unsafe condtons can be created f the system s vented or the helum lnes are dsconnected from the compressor or Opus One unt whle the ether nternal temperature s 280 K. 16

17 5 Detector Operaton Ths chapter descrbes the process of turnng on the detectors and descrbes basc front panel commands for the QO-AMP-SIM electronc control modules. 5.1 Settng Up the Detectors NOTE The output pulses from the nanowre electroncs are postve pulses of ampltude 150 mv or hgher. If negatve pulses are requred, use of a passve pulse nverter such as the PcoQuant SI100 s recommended. The superconductng nanowre detectors operate by applyng a DC bas current slghtly below a threshold swtchng current. Upon absorpton of a photon, the nanowre swtches from a low-resstance superconductng state to a hgh-resstance normal, or non-superconductng, state resultng n rapd ncrease n output voltage. The detector recovers durng a dead-tme before t s ready to detect another photon. The bas current to the each detector s suppled through the electrcal connectons to the NW port of the respectve channel s QO-AMP-SIM module. The voltage pulses generated by photodetecton are amplfed by the QO-AMP-SIM module and output from the OUT ports. Before basng a nanowre, frst make sure t s connected to a QO-AMP-SIM module as descrbed n Chapter 3 and that the module s n standby mode (ndcated by a green lght). Use the followng steps to bas and operate the devce. 1. Connect the QO-AMP-SIM OUT SMA connector to a counter wth a 50 Ω nput mpedance set to 50 mv threshold. 2. The counter should read near zero counts per second at ths pont. If you are seeng hgh counts, there s lkely a ground ssue or electrcal nose from the lab envronment. Please see Chapter 6 for advce on how to correct ths. 3. Press and hold the plus (+) and mnus ( ) buttons untl the lght turns yellow. Upon release of the buttons, the QO-AMP-SIM wll autobas the devce to a hgh dark rate and the lght wll go off. NOTE The electroncs perform an autoreset operaton upon detectng a latch condton on the devce. If the count rate of the devce s too hgh (due to a hgh bas current, too strong optcal flux, or groundng/nose ssue) the lght wll blnk contnuously as the electroncs contnually attempt to reset the devce. Smply decreasng the bas by repeatedly pressng the mnus 17

18 ( ) button should stop ths. The autoreset functon can be dsabled by seral command f desred. 4. Reduce the dark count to 100 to 200 counts per second by repeatedly pressng the mnus ( ) button. The nanowre should now be ready for use. If you are unable to reduce the dark counts to ths level, there s most lkely a groundng/electrcal nose ssue. Please see the troubleshootng advce n Chapter 6. NOTE The nanowres are polarzaton senstve and wll only acheve peak detecton effcency for photons at the optmal polarzaton. Photons polarzed orthogonal to optmum polarzaton wll be detected wth approxmately 50% lower effcency. 5.2 Front Panel Command Reference The QO-AMP-SIM modules perform the basc control tasks for nanowre operaton, and can do so wthout seral control va front-panel operaton. Below s the lst of operatons whch may be performed usng only front-panel control. Bas ON/OFF Press the red ( ) button to turn the bas current on or off. When the bas s turned on, the devce bas current wll be set to the most recent bas setpont snce the module has been powered up. The bas resets to zero upon power up. Increase Bas Press the plus (+) button to ncrease the bas current by one step. The bas ncrement s approxmately 0.4% of the present bas settng. Holdng the button wll rapdly ncrease the bas. Decrease Bas Press the mnus ( ) button to decrease the bas current by one step (n DAC unts). The bas decrement s approxmately 0.4% of the present bas settng. Holdng the button wll rapdly decrease the bas. Autobas Press and hold both the plus (+) and mnus ( ) buttons untl the ndcator lght turns yellow to autobas the nanowre. The bas current wll be ramped up untl the nanowre enters a latched state, the bas s then decreased by approxmately 6% so the devce can operate wth hgh effcency near the maxmum swtchng current. Note that ths bas pont should be consdered a good startng pont for basng the devce but s unlkely to be the optmum pont for your applcaton. Also note that because of slght dfferences n the measured swtchng current the autobas functon may not return to the same bas pont each tme t s run. Store Bas Wth the bas enabled, press and hold the red ( ) and plus (+) buttons to store the current bas level nto nonvolatle memory for later use. Ths stored value s retaned durng power off. 18

19 Load Bas Wth the bas dsabled, press and hold the red ( ) and mnus ( ) buttons to revert the bas level to the value stored n nonvolatle memory. 19

20 6 Troubleshootng If electrcal gltch-nose seems to be contrbutng to the dark count rate, please try the followng suggestons to reduce ths effect. Note that whle the goal s to reduce nose, t s also mportant to note f somethng makes the noses ncrease as t may ndcate where nose s enterng the system 1. Ensure that there s a good connecton between the ground termnal on the back of the SIM900 (banana plug/screw termnal on the rear of the system) and the stanless steel helum lnes on the back of the Opus One unt. 2. Double check that you are usng the provded 12-nch double-shelded SMA cables to connect between the NW SMA connector and the Opus One unt. Ths s the most crtcal electrcal connecton n the system, so the hgh-qualty cables are essental here. 3. Tghten the SMA connectors on the QO-SIM electroncs and the Opus One just tghter than hand-tght (very gently tghten wth a small wrench or SMA torque wrench). If ths connecton s slghtly loose, the nose can be sgnfcantly worse. 4. Remove any swtchng power supples from the AC crcut that powers the Opus One system and SIM900 rack. Major culprts are small, cheaply made power supples that run LED lght strps, moble-phone chargers, and laptops. 5. Dsconnect the GPIB cable from the back of the SIM900 and montor the nose. If the nose drops, work on mprovng the groundng between the computer and the SIM900. In partcular try both confguratons of powerng the computer from the same crcut that runs the SIM900, and from a dfferent crcut to see the change n nose. 6. Try movng other electroncs off of the crcut that powers the SIM900 and montor the nose. 7. If all other suggestons fal: work to move groundng straps or banana cables around to try varous groundng connectons between the SIM900 and the Opus One. Try many groundng locatons ncludng the Opus One front SMA connector shelds, the shelf the system sts on, etc. Ground-loop ssues can be tme-consumng to debug, but dong so may yeld sgnfcant reductons n electrcal nose. 20