Quantenelektronik

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High sensitive bipolar- and high electron mobility transistor read-out electronics for quantum devices.

 Introduction Bipolar-transistor read-out.  PHEMT read-out Motivation Features and construction Measurement setup and procedure Results Verification Discussion Summary

Contents:N. Oukhanski and H.-G. Meyer

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Introduction

Already known read-out technique for quantum devices.Bipolar-transistor read-out.

Easy to match Rsensor with Rnoise of amplifier, TN~80 K.1,2

FET read-out. Minimum TN~2 K @ ~10 kHz, owing RF energy losses.3

SQUID-amplifiers. Minimum TN~1–5 hf/kB. Complex in tuning and setup.4

Pseudomorphic High Electron Mobility Transistor read-out. TN25 K (25 hf/kB)@~20 GHz

for ambient temperatures of 1020 K.5, 6, 7

1. N. Oukhanski, V. Schultze, R. P. J. IJsselsteijn, and H.-G. Meyer, Rev. Sci. Instrum. 74, 12, 5189 (2003).2. N. N. Oukhanski, R. Stolz, V. Zakosarenko, and H.-G. Meyer, Physica C 368, 166 (2002).3. P. Horowitz and W. Hill, Cambridge Univ. Press, 1989, 2nd ed. v. 2, pp. 53–66.4. M. Muck, J. B. Kycia, and J. Clarke, Appl. Phys. Lett. 78, 967 (2001).5. J. Bautista, J. Laskar, P. Szydlik, TDA Progress Report 42-120, 1995.6. J.E. Fernandez, TMO Progress Report 42-135, pp.1-9, November 15, (1998).7. I. Angelov, N. Wadefalk, J. Stenarson, E. Kollberg, P. Starski, H. Zirath, IEEE MTT-S, (2000).

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Bipolar-transistor read-out.

Main features of designed directly-coupled bipolar-transistor electronics

Input voltage white noise level is about 0.32 nV/Hz1/2.Flicker noise corner frequency as low as 0.1 Hz. Current white noise level 6.5 pA/Hz1/2.Wide working temperature range: 77-350 K.One-chip FLL unit solution is resistant to ambient condition, i.e. humidity, convection flows, and temperature radiation.

Very low thermal drift: 30 nV/K (from 15 to 800C).high symmetrical differential circuits for all parts of the FLL-unit used.full design optimization using simulation with software tool of MicroSim-PSpice. SQUID V+

V-

H+

H-Heater

Feed-backcoil

+U-U

Out

Offset

BiasDC

Flux DC

FLL/Reset

Heater

FLL Electronics Control Unit

AD829BufferBuffer1-st

stage

2-d stage

current sourcecurrent source

current source

CINT

RINT

Integrator

RFB1

RFB2

ROFF

RB

RF1

RF2

G20

Functional diagram of the read-out electronics

Prototype (left) and integratedversion of the FLL unit (right).

Gain-bandwidth product fGBP=400 MHz. Three point SQUID biasing possible to reduce voltage drift on the connecting wires to the SQUID.

Power consumption: 80 mW at ±1.5 V.

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Bipolar-transistor read-out.

The maximum bandwidth of 6-8 MHz was measured with several types of low-Tc dc-SQUID magnetometers and gradiometers.Maximum slew rate is in the range

3-9 M0/s. Minimum measured white flux-noise level with SQUID magnetometer of 1.2-1.7 0/Hz1/2 (1-1.4 fT/Hz1/2). A maximum system dynamic range with the SQUID magnetometer is about 155 dB (50 0).Available with high frequency ac-bias technique with frequency up to 10 MHz.1

Flux and field noise spectrum of SQUID magnetometer with sensitivity B/=0.85 nT/ 0 in three layer shielded can. Maximum system dynamic range in FLL mode 50 0.

10-1 100 101 102 103 104 105 106 10710-7

10-6

10-5

10-4

10-3

10-2

1.7 uФ0 / Hz1/2, 1.44 fT / Hz1/2

Flu

x no

ise,

SФ

1/2 , [

Ф0 /

Hz1/

2 ]

Frequency, [Hz]

10-16

10-15

10-14

10-13

10-12

Fie

ld n

oise

, SB

1/2 [

T /

Hz1/

2 ]

Voltage noise spectral density with respect to the input of the integrated electronics at 300 K.

100m 1 10 100 1k 10k100p

1n fcorner

= 0.1 Hz

0.32 nV/Hz1/2

SV [

V/H

z1/2]

Frequency [Hz]

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PHEMT read-out

Already known features.Based on the AlGaAs/InGaAs/GaAs heterostructure.Offers a high transfer coefficient in the microwave frequency range,

owing to the high density and mobility of 2DEG along the layer’s heterojunctions (due to an effect of electron space confinement).

The unique noise characteristics are derived from the 2DEG’s high electron mobility, which is dependent on the electrons scattering process in heterojunctions.

Already measured noise temperatures TN25K (25 hf/kB)@~20 GHz for ambient temperatures of 1020 K.

Originally, expected that the HEMTs would be unsuitable for sensitive measurements at frequencies below 100 MHz, because of the high corner frequency of the flicker noise.

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Motivation

 Desirable area of applicationAreas, which need highly sensitive measurements, such as the characterization of qubit circuits,8-11 bolometric measurements,12,13 SQUIDs2 etc., compel us to search for more sensitive readout methods and devices.

The principle scheme of resonant circuit readout with PHEMT amplifier. Circuit of interest is inductively coupled to the high-Q parallel resonant circuit, with the directly involved through a short line PHEMT.

8. J.E. Mooij, T.P. Orlando, L. Levitov, Lin Tian, van der Wal, S. Lloyd, Science 285, 1036, (1999).9. E. Il’ichev, V. Zakosarenko, L. Fritzsch, R. Stolz, H. E. Hoenig, H.-G. Meyer, A.B. Zorin, V.V. Khanin, M. Götz, A.B. Pavolotsky, and J.

Niemeyer, Rev. Sci. Instr., 72, 1882, (2001).10. E. Il’ichev, Wagner Th., Fritzsch L., Kunert J., Schultze V., May T., Hoenig H. E., Meyer H.-G., Grajcar M., Born D., Krech W., Fistul M.,

Zagoskin A. Appl. Phys. Lett., 80, 4184, (2002).11. E. Ilґichev, N. Oukhanski, A. Izmalkov, Th. Wagner, M. Grajcar, H.-G. Meyer, A. Yu. Smirnov, Alec Maassen van den Brink, M. H. S. Amin,

and A.M. Zagoskin, Phys. Rev. Lett. 91, 9, 097906 (2003).12. D.-V. Anghel and L. Kuzmin, Appl. Phys. Lett. 88, 293-295 (2003).13. L. Kuzmin, Proc. Thermal Detector Workshop, Goddard SFC, Washington DC, (2003), to be published.

UG1 UG2 UG3

USUPP

GROOM

Out

T=300 KT380 mK

L C R

Qubit

From RF generator

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Features of construction

To decrease the power consumption and improve low frequency noise performance:We reduced the transistor’s drain voltage to 0.1 V (2 % of Vds) and the drain current to 200 A (0.3 % of Idss). the first stage power dissipation was only 20 W.

All resistances in the amplifier’s signal channel were replaced by inductances. To protect the amplifier from external and self interferences we used symmetric design. The amplifier was thermally connected to the helium-3 pot of the commercially available refrigerator, “Heliox 2” by Oxford Instruments with temperature below 400 mK.

Two amplifier version, based on the commercial PHEMT ATF-35143, have a common layout and were assembled on a printed board of 33x13 mm2 (see Fig. 2).

Three-stage construction is used to provide the best conditions for minimizing the input noise temperature and back-action to the tank circuit (in the first stage), maximizing the gain factor (second stage), and impedance matching to the input and output lines (first and third stage). Photo of amplifier

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Measurement setup and procedure

USUPP

50 Ohm trans. line,

K5(f)= 0.042dB

loss @ 2.5MHz

50 Ohm divider, K4(f)=

-67.113 dB trans. coeff.@ 2.5MHz

SV

UG3UG2UG1

Room

temperature amplifier

with gain K2(f)

T380 mK

50 Ohm trans. line,

K1(f)=0.042dB loss

@ 2.5MHz

RIN

10 k

Network Analyser HP4396B

PHEMT Amplifier, with gain K3(f)

Measurements with resistor at T0.38 K

To provide a good thermal contact between the

source resistor RIN and 3He pot, a copper finger

was used.

Noise temperature3, 14

SVCOM- input voltage noise spectrum

Measurements with resonant circuit Active resistance of resonant circuit at resonant frequency

The simplified scheme of the amplifier and setup for the noise temperature measurements with resistor (a) and resonant circuit (b).

L C R

T380 mK PHEMT

amplifier

Out

(a)

(b)

1

4 SB

V_COM

TRk

STTN

fKfKfK

SS

321

V_OUT

V_COM

14. N. Oukhanski, M. Grajcar, E. Il’ichev, and H.-G. Meyer, Rev. Sci. Instrum. 74, 1145 (2003).

fC

QfR

π2)( 0S

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Results

Comparison of the voltage noise for the 1st version of cryogenic amplifier with that for the standard room temperature design and rated parameters.

100k 1M 10M 100M100p

1n

10n

Low noise cryogenic design (380mK)

Standard room temperature design (T=300K)

Corner frequency is about 65 MHzCorner frequency

is about 300 kHz

SV

1/2,

[V/H

z1

/2]

Frequency, [Hz]

1M 10M

1m

10m

100m

1

10

1f

10f

100f

1p

10p

0 ,996 1 ,000 1 ,004100p

1nba

SV,

[V/H

z1/2]

N o rm alized F req u en cy , f/f0

TN

SI

1/2

TN min

Error interval

SI1

/2

[A/H

z1/2]

TN,

T N M

IN

[K]

Frequency [Hz]

Measured with resistor TN and calculated current noise SI

1/2 of 1st amplifier version. TN MIN(RS=RN) – estimated minimum noise temperature. Inset are the noise of tank circuit, coupled to the input of the 1st (a) and 2d (b) amplifier version.

1st amplifier version with resistorMeasured minimum TN100 mК@1-4 MHz

with 10 k input resistor.

For used in this case method3,14

TN MIN(RS=RN)=SV1/2SI

1/2/2kB, where RS-real part of input resistance, noise resistance RN=SV

1/2/SI1/2,

SI1/2=(4kBRSTN-SV)1/2/RS,

estimated minimum noise temperature3 is

TN MIN7050 mK5035 hf/kB@30 MHz,

RN21k

With resonant circuit (Q=1510,

f0=28.6 MHz, L=66 nH, C=470 pF, RS(f0)18 k)

Measured upper limit of noise temperature in optimistic case (assuming that RS(f0) associated only to dissipation noise of the tank circuit and amplifier) is

TN(f0)5525 mK (4018 hf/kB).

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Results

Back-action noise:15 Tba=TN-Tad

Additive component Tad (measured without input source),15 originate mainly from drain noise temperature (Td>>TTg),16

back-action component Tba under the influence of drain fluctuations on the tank circuit by means of parasitic capacitor Cgs.

For 1st amplifier version Tba~15 mK

Sv-measured with shorted input voltage noise.

Very high sensitivity applications, where a drain current and/or voltage fluctuation can increase the gate temperature, or can decrease the decoherence time of an input signal, impose strong requirements on Tba

2d amplifier version with resonant circuit (Q=2080, f0=26.77 MHz, L=177 nH, C=200 pF, RS(f0)=61.8 kOhm,) Assuming RS(f0) associated only to dissipation noise: TN(f0)7330 mK at ambient temperature T=370 mKBack-action noise temperature: Tba=TN-Tad~10 mK

UG1

USUPP

L C R

T380 mK

TdgmVgs Rds

Cgs

Rs

Cgd

Rgs

Drain

Source

Gate

Rg

Tg

Rd

15. A. Vinante, M. Bonaldi, M. Cerdonio, P. Falferi, R. Mezzena, G. A. Prodi, and S. Vitale, Classical and Quantum Gravity, 19, Is. 7, p. 1979 (2002).16. M. W. Pospieszalski IEEE Trans. on Microwave Theory and Techniques, 37, no. 9, pp. 1340-1350 (1991).

Variant of the 1st stage with the lowest designed back-action.

1

4 SB

VV_COM

TRk

SSTTba

Simplified small-signal circuit diagram of PHEMT.

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Verification

To be convinced in our estimation we used amplifier noise model based on the definition of voltage and current noise, as SV=2kBTNRN and SI=2kBTN/RN.17 Assuming RS(f0) associated only to dissipation noise, noise temperature:

TN(f0)=(SVCOM(f0)-4kBTRS)RN/(2kB(RS2+RN

2))(SV SI)1/2/(2kB).

17. T. Ryhanen and H. Seppa, J. Low Temp. Phys. 76, 287 (1989).

Measurements procedure TN for 1st version RN TN for 2d version RN

TN=T(SV_COM/(4kTRS)-1) 7050 mK@30 MHzwith 10 kOhm resistor

21 kOhm - -

TN=T(SV_COM/(4kTRS)-1)With resonant circuit

5525 mK@29 MHzwith Rs(f0)=18 kOhm

7330 mK@27 MHzwith Rs(f0)=62 kOhm

SV=2kBTNRN, SI=2kBTN/RN

With resonant circuit4825 mK@29 MHzwith Rs(f0)=18 kOhm

30 kOhm 5330 mK@27 MHzwith Rs(f0)=62 kOhm

140 kOhm

SV

SI

GL C RS

Rd L C RcSV

SI

GSuppose the worst case, when RS(f0) associated with dissipation noise of common resistance (Rd and Rc) and contribution of damping cold resistance from amplifier Rc. Hence SI=(SVCOM-SV)/RS-4kBT/Rd. Taking into account: 1.Maximum quality factor, measured between available tank circuits, with both system (Q2040, f027 MHz, C=100 pF and Q3340, f025 MHz, C=100 pF correspondingly). 2.Absence of voltage flicker noise in the working frequency range on the ceramic capacitors which we used in our resonant circuits. The pessimistic value for the noise temperature in this case TN(f0)=(SVSI)1/2/(2kB):

TN(f0)=110 mK, and 170 mK for the 1st and 2d variant of electronics correspondingly.

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Discussion

6.280M 6.282M 6.284M 6.286M 6.288M 6.290M 6.292M500.0p

600.0p

700.0p

800.0p

900.0p

1.0n

1.1n

1.2n

1.3n

1.4n

1.5n

Without high frequency power

Sv1

/2

T c

ircuit, [V

/Hz1/2]

Frecuency, [Hz]

By taking into account tank circuit quality factor Q=2080 (2d variant of amplifier), this setup gives us an opportunity to perform quantum level measurements with periodical signals, even if the coupling coefficient of the thank circuit to the sensor is less than 1. It is necessary to note, that available in real condition tank circuit impedance can be far from optimum value, which can noticeably increase setup noise temperature.

Measurements with Qubit, TN270 mK, amplifier ambient temperature ~2 K

18. M. Grajcar, A. Izmalkov, E. Il'ichev, Th. Wagner, N. Oukhanski, U. Huebner, T. May, I. Zhilyaev, H.E. Hoenig, Ya.S. Greenberg, V.I. Shnyrkov, D. Born, W. Krech, H.-G. Meyer, Alec Maassen van den Brink, and M.H.S. Amin, Phys. Rev. B 69, 060501(R) (2004).19. A. Izmalkov, M. Grajcar, E. Il'ichev, N. Oukhanski, Th. Wagner, H.-G. Meyer, W. Krech, M.H.S. Amin, Alec Maassen van den Brink, A.M. Zagoskin, Europhys. Lett., 65 (6), pp. 844–849 (2004).

The second version of the amplifier placed at temperature 2 K was successfully employed for different quantum measurements.11, 18, 1 9

By taking into account system bandwidth f=100 MHz and rating quality factor Q1000@30 MHz estimated available number of cannels 1000 with f100 kHz.

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 Summary

Integrated version of direct coupled bipolar-transistor dc SQUID read-out electronics with minimum noise temperature TN=80 K is presented.

Very low thermal drift (30 nV/K) of the electronics and the low corner frequency of flicker noise (0.1 Hz) is useful for realization of long-time experiments.

Wide working temperature range of read-out electronics (77–350 K) provides system reliability at any climatic conditions.

High slew rate (up to 9 M0/s) and sensitivity (0.32 nV/Hz1/2), large bandwidth (6 MHz) and system dynamic range at using of long cable between the sensor and electronics (about of 1–2 meters) well suited for high-precision measurements at unshielded conditions.

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 Summary and acknowledgment

Two versions of a cryogenic PHEMT amplifier designed for quantum device readout and tested at an ambient temperature 380 mK. Noise temperature of the 1st amplifier version is below 11050 mK (8040 hf/kB)@28.6 MHz, estimated from the noise of a coupled input tank

circuit with resistance RS(f0)18 kOhm at the resonant frequency.

Its minimum input voltage spectral noise density is 200 pV/(Hz)1/2 and the corner frequency of the 1/f noise is close to 300 kHz. For the amplifier with the lowest designed back-action, the noise temperature below 17070 mK (15060 hf/kB)@26.8 MHz was measured when coupled

to an input tank circuit with RS(f0)62 kOhm.

The amplifiers’ power consumption is in the range of 100–600 W. The second version of the amplifier with ambient temperature 2 K was successfully employed for different quantum measurements.The authors gratefully acknowledge the discussions and help on the different stages of work of H. E. Hoenig, E. Il'ichev, V. Zakosarenko, R. Stolz, M. Grajcar, Th. Wagner, A. Izmalkov, S. Uchaikin and R. Boucher.