DE102019116276A1 - Device for detecting individual light quanta - Google Patents

Abstract

In the case of a device for detecting individual light quanta by means of at least one superconducting single photon detector (2), a solution is to be created to reduce the ohmic losses and the noise component of a driver circuit (3) for controlling the superconducting single photon detector (2) to enable fast switching times. This is achieved in that the device comprises a superconducting single photon detector (2), comprises a driver circuit (3), the driver circuit (3) being set up to provide a triggered bias current for the superconducting single photon detector (2), the device is set up to cool the superconducting single photon detector (2) and the driver circuit (3) to a temperature suitable for the superconducting of the superconducting single photon detector (2). The invention also relates to a method for detecting individual light quanta by means of a device described above. The invention also relates to the use of the device in laser-induced fluorescence spectroscopy.

Description

The invention relates to a device for detecting individual light quanta, in particular a device for detecting individual light quanta by means of at least one superconducting single photon detector. The invention also relates to a method for detecting individual light quanta by means of the device according to the invention. The invention also relates to the use of the device in laser-induced fluorescence spectroscopy.

Superconducting single photon detectors (SSPDs) are the most promising alternative to traditional single photon detectors. Their high saturation numbers, small timing jitter, wide wavelength detection range, and low dark count rates make them promising candidates in a wide variety of applications. Single photon detectors are the basis of quantum optics and quantum information. Telecommunications, medical imaging and biophotonics are further intended areas of application for superconducting single photon detectors.

Superconducting single photon detectors have a high performance in free-running operation, but have a limited maximum count rate and a dead time after each counting event. In some applications, however, the bias current of the superconducting single photon detector must be limited in order to reduce the count rates of noise or transient overdrive. The noise count rates can be obtained from other light sources of the experiment e.g. B. originate in the pump-probe spectroscopy, as well as from dark noise. The detector is controlled synchronously with the timing of the overall system. This control of the detector can increase the signal-to-noise ratio by enabling a larger current and thus a higher detection efficiency in a short time window if a photon is expected without suffering from great dark noise if no photon is expected. By using a gated mode operation of the detector, the counting rate of the useful signal can be increased while the dark counting rate is reduced at the same time.

The detector is controlled by means of a driver circuit, with the superconducting single photon detector being energized during gated mode operation by a triggered bias current instead of a constant bias current.

Various driver circuits for controlling a superconducting single photon detector are known from the prior art. The disadvantage of the driver circuits known from the prior art is that these driver circuits have high ohmic losses, short switching times and a high proportion of noise.

The invention is therefore based on the object of creating a solution which makes it possible to provide a device for detecting individual light quanta by means of at least one superconducting single photon detector, the ohmic losses of the driver circuit and the noise component being reduced, fast switching times being made possible and dead times transient overload can be avoided.

In a device for detecting individual light quanta by means of at least one superconducting single photon detector of the type described at the outset, the object is achieved according to the invention in that the device comprises at least one superconducting single photon detector, the device further comprises at least one driver circuit, the driver circuit being set up in such a way, a triggered Provide a bias current for the superconducting single photon detector, the device being set up to cool the superconducting single photon detector and the driver circuit to a temperature suitable for superconducting the superconducting single photon detector.

Such a device for detecting individual light quanta by means of at least one superconducting single photon detector makes it possible to realize very fast switching times of the superconducting single photon detector. This makes it possible to perform gating on a time scale (≈10 ps), which is far below the dead time that results from the system-related recovery time from the normally conducting to the superconducting state (≈10 ns).

In a preferred embodiment of the invention, the driver circuit is coupled ohmically to the superconducting single photon detector.

In a further preferred embodiment of the invention, the superconducting single photon detector is controlled in a unipolar manner by means of the driver circuit.

In a preferred embodiment of the invention, the superconducting single photon detector is driven bipolar by means of the driver circuit. The bipolar coupling of the detector offers the advantage that, starting from the detecting state, the detector can be switched back to the detecting state transiently via the off state, thereby enabling extremely short off states of the detector.

In a further preferred embodiment of the invention, the driver circuit is coupled to the superconducting single photon detector capacitively. Since no ohmic attenuators are required in this embodiment of the invention, there is negligible dissipation.

In a preferred embodiment of the invention, the driver circuit is coupled to the superconducting single photon detector capacitively via a current node.

In a further preferred embodiment of the invention, the driver circuit and the at least one superconducting single photon detector are implemented on a single integrated circuit chip. Completely integrated photonic circuits with all main components on a single chip are an important step on the way to new technologies such as quantum photonics or quantum sensors. By integrating the driver and control electronics with photonic circuits and detectors on the same chip, the packaging complexity and costs are greatly reduced. Furthermore, the integration offers the advantage that the driver and control electronics can easily be brought to the temperature suitable for superconductivity.

In a particularly preferred embodiment of the invention, the driver circuit is a CMOS driver circuit. The advantage here is that in addition to the photonic circuits, the driver and control electronics can also be integrated on a chip using established manufacturing techniques, for example for complementary metal oxide semiconductors (CMOS). This facilitates the integration of CMOS-based microelectronics, driver and control electronics, and photonic circuits on the same chip. By using CMOS-based manufacturing techniques, single photon detectors can also be integrated on the chip with silicon that is compatible with superconductors, which enables the measurement-induced non-linear interaction between individual photons.

• - Bereitstellen zumindest eines supraleitenden Einzelphotonendetektors (2),
• - Bereitstellen zumindest einer Treiberschaltung (3),
• - Kühlung des supraleitenden Einzelphotonendetektors (2) und der Treiberschaltung (3) auf eine für die Supraleitung des supraleitenden Einzelphotonendetektors (2) geeignete Temperatur,
• - Bestromung des supraleitenden Einzelphotonendetektors (2) mittels der Treiberschaltung (3), wobei die Bestromung des supraleitenden Einzelphotonendetektors (2) getriggert erfolgt.

According to the invention, a method for detecting individual light quanta by means of a device described above is also specified with the following steps:

• - Provision of at least one superconducting single photon detector ( 2 ),
• - Provision of at least one driver circuit ( 3 ),
• - Cooling of the superconducting single photon detector ( 2 ) and the driver circuit ( 3 ) on one for the superconductivity of the superconducting single photon detector ( 2 ) suitable temperature,
• - Current supply to the superconducting single photon detector ( 2 ) by means of the driver circuit ( 3 ), whereby the current flow to the superconducting single photon detector ( 2 ) triggered.

In a preferred embodiment of the invention, the step of energizing the superconducting single photon detector takes place synchronously with the timing of the device. The superconducting single photon detector can also be supplied with current as a result of the reaction to certain events or coincidences. Examples of this are the reaction to the result of a previous quantum measurement or the reaction to an impending overdrive state that is to be prevented by blanking the current supply.

In a further preferred embodiment of the invention, the step of energizing the superconducting single photon detector takes place in response to an external event.

In a further preferred embodiment of the invention, the coupling between the superconducting single photon detector and the driver circuit is capacitive, the step of energizing the superconducting single photon detector by means of the driver circuit including energization by means of displacement currents.

The use of the device according to one of the claims described above in laser-induced fluorescence spectroscopy is also in accordance with the invention.

Further details, features and advantages of the subject matter of the invention emerge from the subclaims and from the following description of the associated drawings.

• 1 ein Schaltbild einer Vorrichtung zum Erfassen von einzelnen Lichtquanten mittels zumindest eines supraleitenden Einzelphotonendetektors mit einer getriggerten Bias-Strom Erzeugung für den supraleitenden Einzelphotonendetektor mittels Tieftemperatur-Treiberschaltung gemäß einem ersten Ausführungsbeispiel der Erfindung mit unipolarer, ohmscher Ansteuerung,
• 2 ein Schaltbild einer Vorrichtung zum Erfassen von einzelnen Lichtquanten mittels zumindest eines supraleitenden Einzelphotonendetektors mit einer getriggerten Bias-Strom Erzeugung für den supraleitenden Einzelphotonendetektor mittels Tieftemperatur-Treiberschaltung gemäß einem zweiten Ausführungsbeispiel der Erfindung mit bipolarer, ohmscher Ansteuerung,
• 3 ein Diagramm einer Bestromung eines supraleitenden Einzelphotonendetektors,
• 4 ein Schaltbild einer Vorrichtung zum Erfassen von einzelnen Lichtquanten mittels zumindest eines supraleitenden Einzelphotonendetektors mit einer getriggerten Bias-Strom Erzeugung für den supraleitenden Einzelphotonendetektor mittels Tieftemperatur-Treiberschaltung gemäß einem dritten Ausführungsbeispiel der Erfindung mit kapazitiv gekoppeltem Gating-Puls,
• 5
  • a) ein Diagramm des zeitlichen Verlaufs der Ausgangsspannung der Tieftemperatur- Treiberschaltung,
  • b) ein Diagramm des zeitlichen Stromverlaufs des Stroms I₁,
  • c) ein Diagramm des zeitlichen Stromverlaufs des Stroms I₂,
• 6 ein Schaltbild einer Vorrichtung zum Erfassen von einzelnen Lichtquanten mittels zumindest eines supraleitenden Einzelphotonendetektors mit einer getriggerten Bias-Strom Erzeugung für den supraleitenden Einzelphotonendetektor mittels Tieftemperatur-Treiberschaltung gemäß einem vierten Ausführungsbeispiel der Erfindung,
• 7
  • a) ein Diagramm des zeitlichen Verlaufs der Ausgangsspannung der Treiberschaltung,
  • b) ein Diagramm des zeitlichen Verlaufs des Verschiebestroms I₁,
• 8 ein Schaltbild der Verwendung einer Vorrichtung zum Erfassen von einzelnen Lichtquanten mittels zumindest eines supraleitenden Einzelphotonendetektors bei der Laser-Streulicht Unterdrückung in der Zeitdomäne durch ultraschnelles, getriggertes Bias-Gating erfolgt,
• 9
  • a) ein Diagramm des zeitlichen Verlaufs eines Laserpulses,
  • b) ein Diagramm des zeitlichen eines Bias-Strom Gating eines supraleitenden Einzelphotonendetektors,
  • c) ein Diagramm des zeitlichen Verlaufs der Lumineszenz mit Laser-Streulicht,
  • d) ein Diagramm des zeitlichen Verlaufs der detektierten Lumineszenz.

Show it:

• 1 a circuit diagram of a device for detecting individual light quanta by means of at least one superconducting single photon detector with a triggered bias current generation for the superconducting single photon detector by means of a low-temperature driver circuit according to a first embodiment of the invention with unipolar, ohmic control,
• 2 a circuit diagram of a device for detecting individual light quanta by means of at least one superconducting single photon detector with a triggered bias current generation for the superconducting single photon detector by means of a low-temperature driver circuit according to a second Embodiment of the invention with bipolar, ohmic control,
• 3 a diagram of an energization of a superconducting single photon detector,
• 4th a circuit diagram of a device for detecting individual light quanta by means of at least one superconducting single photon detector with a triggered bias current generation for the superconducting single photon detector by means of a low-temperature driver circuit according to a third embodiment of the invention with a capacitively coupled gating pulse,
• 5
  • a) a diagram of the time course of the output voltage of the low-temperature driver circuit,
  • b) a diagram of the current course of the current I _{1 over time} ,
  • c) a diagram of the temporal course of the current I ₂ ,
• 6th a circuit diagram of a device for detecting individual light quanta by means of at least one superconducting single photon detector with a triggered bias current generation for the superconducting single photon detector by means of a low-temperature driver circuit according to a fourth embodiment of the invention,
• 7th
  • a) a diagram of the time profile of the output voltage of the driver circuit,
  • b) a diagram of the time course of the displacement current I ₁ ,
• 8th a circuit diagram of the use of a device for detecting individual light quanta by means of at least one superconducting single photon detector in the case of laser scattered light suppression in the time domain by ultra-fast, triggered bias gating,
• 9
  • a) a diagram of the time course of a laser pulse,
  • b) a diagram of the temporal bias current gating of a superconducting single photon detector,
  • c) a diagram of the time course of the luminescence with laser scattered light,
  • d) a diagram of the time course of the detected luminescence.

The 1 shows a circuit diagram of a device for detecting individual light quanta by means of at least one superconducting single photon detector 2 with a triggered bias current generation for the superconducting single photon detector 2 by means of low temperature driver circuit 3 according to a first embodiment of the invention. The device comprises a superconducting single photon detector 2 , the energization of the superconducting single photon detector 2 by a bias current gating by means of a driver circuit 3 and an ohmic attenuator 8th he follows. At least the driver circuit 3 as well as the superconducting single photon detector 2 are together in a low temperature range 1 arranged, the low temperature range 1 is an area that is one for superconductivity of the superconducting single photon detector 2 has a suitable temperature. The driver circuit 3 can for example be a CMOS driver circuit, it can be advantageous if the driver circuit 3 and the superconducting single photon detector 2 implemented on a single integrated circuit chip or on a common chip carrier.

This allows the driver circuit 3 and the superconducting single photon detector 2 at the same time be brought to the temperature required for superconductivity in a simple manner. CMOS technology also offers the advantage that silicon single photon detectors compatible with superconductors can also be integrated on the chip using these manufacturing techniques. In the 1 The device shown also has a trigger input 4th with terminating resistor 6th , being through the trigger input 4th the driver circuit 3 with supply voltage 5 a trigger signal for triggered bias gating is made available. The device also has an output 7th on which a measurement signal from the superconducting single photon detector 2 can be tapped. The exit 7th can, for example, be connected to a counter that registers the measurement signals of individual photons.

The coupling of the superconducting single photon detector 2 to the driver circuit 3 takes place in the in 1 Circuit diagram shown ohmic via an attenuator 8th , where in 1 the control of the superconducting single photon detector 2 unipolar. With unipolar control, the superconducting single photon detector 2 from the off state to the detecting state switched or switched from the detecting state to the off state.

The 2 shows a circuit diagram of a device for detecting individual light quanta by means of at least one superconducting single photon detector 2 with a triggered bias current generation for the superconducting single photon detector 2 by means of low temperature driver circuit 3 according to a second embodiment of the invention. At the in 2 The device shown is the coupling of the superconducting single photon detector 2 to the driver circuit 3 also ohmic. The control takes place in the in 2 However, the circuit diagram shown is bipolar. In the bipolar case, the superconducting single photon detector is used 2 starting from the detecting state, transiently switched back to the detecting state via the non-detecting state. This enables extremely short off-states. To establish the bipolar operating mode, the connection 12 a DC voltage is provided across the resistor 9 a bias current at the single photon detector 2 generated for the on and off state of the driver circuit 3 is the same in terms of amount, but has a different sign. When switching from the on to the off state, a transient non-detecting state results.

The device also has the outputs 10 and 11 , on which positive and negative measurement signals of the superconducting single photon detector 2 can be tapped. The outputs are used to count all photon-induced measurement signals 10 and 11 two discriminators with uniformly positive or uniformly negative threshold voltage supplied. After a logical AND operation, their output signals supply the entire counting events regardless of the sign of the bias current.

To establish the bipolar operating mode, the passive setting of the bias current can be done via connection 12 be replaced by an active variant in which the active control of the superconducting single photon detector 2 by means of driver circuit 3 and attenuator 8th is made on both sides. In the case of complementary switching processes between the on and off state, transiently non-detecting states result, the duration of which can be set by controlling the switching process.

In 3 Figure 12 is a diagram of energization of a superconducting single photon detector 2 shown, with the energization of the superconducting single photon detector 2 versus the quantum efficiency of the superconducting single photon detector 2 is applied.

The in 3 Case a) shown shows the unipolar control of the superconducting single photon detector 2 . The superconducting single photon detector 2 is switched 31 from the off state to the detecting state.

Case b) shows the bipolar control of the superconducting single photon detector 2 . The superconducting single photon detector 2 is switched from the detecting state transiently via the non-detecting state back to the detecting state 30th .

The 4th shows a circuit diagram of a device for detecting individual light quanta by means of at least one superconducting single photon detector 2 with a triggered bias current generation for the superconducting single photon detector 2 by means of low temperature driver circuit 3 according to a third embodiment of the invention. The in 4th The circuit diagram shown is used to couple the superconducting single photon detector 2 with the driver circuit 3 capacitive. The coupling takes place by means of a coupling capacitor 40 . The coupling capacitor 40 can with short rise times of the driver circuit 3 (≈ 10 ¹¹ V / s), for example, have a capacity between 10 ^-14 to 10 ^-16 farads.

The bias current is in the detecting state 41 via one at the entrance 42 applied DC voltage and the series resistance 43 (≈50 Ohm) embossed. The condenser 44 is used for HF decoupling. The bias current flows in the detecting state 41 about the very low resistance 45 (≈1 ohm) at full strength 46 further to the superconducting single photon detector 2 .

When switching the driver circuit 3 from the on to the off state occurs via the coupling capacitor 40 a transient displacement current 47 , the one at the power node 48 the bias current 41 from the superconducting single photon detector 2 to the coupling capacitor 40 redirects. The low resistance 45 between the superconducting single photon detector and the power node allows the voltage at the power node 48 can be pulled transiently to zero or even below zero and thus the bias current can be diverted. Since the in 4th the embodiment shown, no attenuator is required, the dissipation is negligible.

The 5 a) shows a diagram of the time profile of the output voltage of the low-temperature driver circuit 3 .

The 5 b) shows a diagram of the temporal course of the current I ₁ 46 .

The 5 c) shows a diagram of the temporal course of the current I ₂ 47 .

The 6th shows a circuit diagram of a device for detecting individual light quanta by means of at least one superconducting single photon detector 2 with a triggered bias current generation for the superconducting single photon detector 2 by means of low temperature driver circuit 3 according to a fourth embodiment of the invention. At the in 6th The device shown is the superconducting single photon detector 2 with the driver circuit 3 capacitive via the coupling capacitor 40 coupled. The control of the superconducting single photon detector 2 takes place in this circuit via an output voltage of the driver circuit 3 , whereby the output voltage has temporally predetermined ranges, the defined displacement currents 60 generated. The counting events triggered by individual photons are shown at the output 7th with the terminating resistor 61 detected.

In 7 a) is the time course of the output voltage of the driver circuit 3 shown. The superconducting single photon detector is located in the areas where the voltage is constant 2 in the off state. In the falling and rising areas of the voltage curve, the derivation of the voltage over time results in in 7 b) displacement currents shown 60 . Through the shift currents 60 becomes the superconducting single photon detector 2 switched to the detecting state and measurements of the count rate of the detector are possible.

In 8th is a circuit diagram of the use of a device for detecting individual light quanta by means of at least one superconducting single photon detector 86 shown for laser scattered light suppression in the time domain by ultra-fast (≈30 ps), triggered bias gating in laser-induced fluorescence spectroscopy. Superconducting single photon detector 86 are very suitable for measurements in laser-induced fluorescence spectroscopy. In laser-induced fluorescence spectroscopy, an atom, molecule or substance is exposed to a laser beam 88 If the light has a frequency from the absorption range of the substance, the laser excitation results in fluorescence. In the 8th The device shown thus comprises a laser 80 for sending laser pulses 88 . The laser pulses 88 are made by means of a first beam splitter 81 divided into two partial beams, a first partial beam hits a photodetector 82 having an electrical trigger signal 85 provides. This trigger signal 85 is used for triggered bias gating of a superconducting single photon detector 86 used. The driver circuit required for the triggered bias gating and the superconducting single photon detector 86 are arranged together in a low-temperature range, the low-temperature range being an area which has a temperature suitable for superconductivity.

The second partial beam is generated by means of a second beam splitter 89 on a trial 84 steered to excite the luminescence. The one from the rehearsal 84 Radiated luminescence is generated via deflection mirrors 83 the superconducting single photon detector 86 made available and the signals of the superconducting single photon detector, for example by means of a time tagger 87 recorded.

In 9 is the time course of the laser pulse a), the bias current gating of the superconducting single photon detector 86 b), the luminescence with laser scattered light c) and the superconducting single photon detector 86 measured luminescence d) shown.

9 a) shows the laser pulse 88 which is responsible for the excitation of the luminescence on the sample 84 is irradiated. Because the laser pulse 88 beforehand by means of a first beam splitter 81 and a photodetector 82 a trigger signal 85 was assigned, is the superconducting single photon detector 86 switched from a detecting state to the off state by means of the trigger signal. This is done by means of a triggered bias gating which is implemented in 9 b) is shown. During the irradiation of the laser pulse 88 is the superconducting single photon detector 86 switched to the off state. Because of the laser light 88 becomes the sample 84 excited to luminescence. In 9 c) is the luminescence of the sample 84 as well as remnants of the excitation light 88 , which is recognizable as laser scattered light as a peak in the course of the curve over time. Due to the triggered bias current gating of the superconducting single photon detector 86 the area in which unwanted laser scattered light occurs is effectively suppressed. As in 9 d) shown is the measurement of luminescence by means of the superconducting single photon detector 86 only on after the laser scattered light has already subsided, whereby the suppression of the laser scattered light in the time domain is realized.

The invention on which this patent application is based arose from research that was funded by the BMBF through the projects "Q.Link.X" and "Quantum Future ISOQC".

List of reference symbols

1

Low temperature range

2

superconducting single photon detector

3

Driver circuit

4th

Trigger

5

Supply voltage driver circuit

6th

Terminating resistor

7th

exit

8th

Resistive attenuator

9

resistance

10

exit

11

exit

12

Voltage input for generating the bias current

30th

unipolar control range

31

bipolar control area

40

Coupling capacitor

41

Bias current

42

Voltage input for generating the bias current

43

Series resistance

44

Condenser for HF decoupling

45

Low resistance

46

Bias current to the detector

47

Transient displacement current

48

Power node

60

Displacement current I ₁

61

Terminating resistor

80

ps laser

81

first beam splitter

82

MSM photodetector

83

Deflection mirror

84

Luminescent sample

85

Electrical trigger signal

86

SSPD with CMOS gating

87

Time tagger

88

Laser pulse

89

second beam splitter

Claims (13)

Device for detecting individual light quanta by means of at least one superconducting single photon detector (2) comprising: at least one superconducting single photon detector (2), at least one driver circuit (3), wherein the driver circuit (3) is set up to provide a triggered bias current for the superconducting single photon detector (2), wherein the device is set up to cool the superconducting single photon detector (2) and the driver circuit (3) to a temperature suitable for the superconducting of the superconducting single photon detector (2). Device according to Claim 1 characterized in that the driver circuit (3) is coupled to the superconducting single photon detector (2) in an ohmic manner. Device according to Claim 2 characterized in that the superconducting single photon detector (2) is controlled unipolar by means of the driver circuit (3). Device according to Claim 2 characterized in that the superconducting single photon detector (2) is controlled bipolar by means of the driver circuit (3). Device according to Claim 1 characterized in that the driver circuit (3) is coupled to the superconducting single photon detector (2) capacitively. Device according to Claim 5 characterized in that the driver circuit (3) is coupled to the superconducting single photon detector (2) capacitively via a current node (48). Device according to one of the preceding claims, characterized in that the driver circuit (3) and the at least one superconducting single photon detector (2) are implemented on a single integrated circuit chip. Device according to one of the preceding claims, characterized in that the driver circuit (3) is a CMOS driver circuit. Method for detecting individual light quanta by means of a device according to one of the Claims 1 to 8th with the following steps: - providing at least one superconducting single photon detector (2), - providing at least one driver circuit (3), - cooling the superconducting single photon detector (2) and the driver circuit (3) to a temperature suitable for superconducting the superconducting single photon detector (2) - energization of the superconducting single photon detector (2) by means of the driver circuit (3), the energization of the superconducting single photon detector (2) being triggered. Procedure according to Claim 8 characterized in that the step of energizing the superconducting single photon detector (2) takes place synchronously with the timing of the device. Procedure according to Claim 8 characterized in that the step of energizing the superconducting single photon detector (2) takes place in response to an external event. Method according to one of the Claims 9 to 11 characterized in that the coupling between the superconducting single photon detector (2) and the driver circuit (3) takes place capacitively, the step of energizing the superconducting single photon detector (2) by means of the driver circuit (3) includes energization by means of displacement currents. Use of the device according to one of the Claims 1 to 8th in laser-induced fluorescence spectroscopy.

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