Aluminium Kinetic Inductance Detectors at 1.54 THz limited by photon noise and

generation-recombination noise

Pieter de Visser, Jochem Baselmans, Juan Bueno, Nuria Llombart, Teun Klapwijk

SRONTU Delft, Faculty of Applied SciencesTU Delft, Faculty of Electrical Engineering Mathematics and Computer Siences

Optical Noise Equivalent Power @ 1.54 THz

10-6

10-4

10-2

100

102

10-19

10-18

10-17

10-16

Optical Power (fW)

Opt

ical

NE

P (W

/Hz1/

2 )

Measured Optical NEPPhoton Noise NEPPhoton Noise NEP+ Excess-qp GR-Noise

GR - NoisePhoton Noise

Operation principle

F0f

S21

[dB

]

F [Ghz] Day et al, Nature 425, 817 (2003)

2Δ

Cooper Pairs

Quasiparticles

h

Photons break Cooper pairs => quasiparticlesHigher resistance and kinetic inductanceDip depth / amplitude: resistanceResonant frequency / phase: inductance

Anticipated fundamental limits

KID is a pair breaking detector: fluctuations in the quasiparticle number• Photon noise (= generation noise)• Recombination noise

• Generation-recombination noise

Prediction from dark experiments: NEP of 2 x 10-19 W/Hz1/2 limited by the presence of excess quasiparticles

DesignAll Aluminium KID• Central Line: 50 nm Al• Groundplane: 100 nm Al• Halfwave resonator with isolated central strip• X-slot Antenna, broad band around 1.54 THz• 2 mm silicon elliptical lenses

Design suitable for higher frequencies >1.54 THz

Controlled optical setup

8 optical filters! Box-in-box setupBaselmans et al. JLTP 167, 360 (2012)J. Bueno, Poster 106 (Thursday)

Large range in optical power

Fundamental limit: Photon Noise

101 102 103 104 105-100

-95

-90

-85

-80

-75

Pow

er s

pect

ral d

ensi

ty (d

Bc/

Hz)

Frequency (Hz)

3 zW459 zW26 aW3 fW34 fW142 fW724 fW

10-6 10-4 10-2 100 102

10-4

10-3

Qua

sipa

rticl

e lif

etim

e (s

)

Optical Power (fW)

105

106

Num

ber o

f qua

sipa

rticl

es

MeasurementsFit

Optical Power (fW)

Random arrival rate of the optical photons

+ recombination noise

𝑆 𝐴=2 h𝑃 𝐹 ( 𝑑𝐴𝑑 𝑃 )2 11+(2𝜋 𝑓 τ )2

Recombination time scales with as expected

Generation-recombination noise

De Visser et al. PRL 106, 167004 (2011)Wilson & Prober, PRL, 87, 067004 (2001)

Quasiparticle fluctuations

101 102 103 104 105

-95

-90

-85

-80

Frequency (Hz)

Am

plitu

de P

SD

(dB

c/H

z)

90 mK150 mK180 mK210 mK240 mK255 mK

100 150 200 250

10-4

10-3

Qua

sipa

rticl

e lif

etim

e (s

)

Temperature (mK)

105

106

Num

ber o

f qua

sipa

rticl

es

MeasurementsTheory

2

2 2 2 2

4 41 1NN NS

𝑁𝐸𝑃 h𝑝 𝑜𝑡𝑜𝑛=√2 h𝑃 𝐹η𝑜𝑝𝑡

101

102

103

104

105

10-19

10-18

10-17

10-16

Am

plitu

de N

EP

(W/H

z1/

2 )

Frequency (Hz)

3 zW43 zW455 zW4 aW26 aW123 aW434 aW3 fW34 fW142 fW366 fW724 fW

Optical Noise Equivalent Power

10-6

10-4

10-2

100

102

10-19

10-18

10-17

10-16

Optical Power (fW)O

ptic

al N

EP

(W/H

z1/2 )

Measured Optical NEPPhoton Noise NEPPhoton Noise NEP+ Excess-qp GR-Noise

GR - Noise

Photon Noise

Photon noise limited NEP => Measure of optical efficiency: 48%

𝑁𝐸𝑃= √𝑆𝑝𝑒𝑐𝑡𝑟𝑢𝑚𝑅𝑒𝑠𝑝𝑜𝑛𝑠𝑖𝑣𝑖𝑡𝑦 (1+ (2𝜋 𝑓 τ )2)

Optical responsivity + lifetime: Microwave readout power dependent

-110 -105 -100 -95 -90

1014

1015

Microwave readout power (dBm)

Am

plitu

de R

espo

nsiv

ity (W

-1)

Measurementsfit

-102 -98 -94 -901.5

2

2.5

3

3.5

4

Microwave readout Power (dBm)

Qua

sipa

rticl

e lif

etim

e (m

s)De Visser et al. APL 100, 162601 (2012)Goldie, SuST, 26, 015004 (2013)

Microwave readout power: Excess quasipartilces AND nonlinear reponse due to

redistribution of quasiparticles

arXiv: 1306.4992

Poster 104 (Monday)

104

105

106

107

Inte

rnal

Qua

lity

Fact

or

Model -100 dBm -80 dBm -72 dBm

0.1 0.15 0.2 0.25 0.3 0.355.288

5.2885

5.289

5.2895

Temperature (K)

Res

onan

t Fre

quen

cy (G

Hz)

Measurement-100 dBm-90 dBm-80 dBm-72 dBm-68 dBm-64 dBm

(b)

0

0.05

0.1

0.15

0.2

E/

103

f E

120 mK

1 2 3 4 510

-3010

-2010

-10

E/

f E

1 1.2 1.4 1.6 1.8 20

0.5

1

1.5

E/10

3 f E

320 mK

1 2 310

-810

-610

-4

E/

f E

-100 dBm-80 dBm-72 dBmThermal

Summary• Kinetic Inductance Detector at 1.54 THz

– Fundamental noise sources for pair breaking detectors revealed:

• Photon noise limited• Generation-recombination noise => excess quasiparticles

– NEP 3.8 x 10-19 W/Hz1/2, 48% optical efficiency • Well controlled optical setup, large power range

1.54 THz experiment - arXiv:1306.4238Microwave response - arXiv:1306.4992

KID at 1.54 THz

10-6

10-4

10-2

100

102

10-19

10-18

10-17

10-16

Optical Power (fW)

Opt

ical

NE

P (W

/Hz1/

2 )

Measured Optical NEPPhoton Noise NEPPhoton Noise NEP+ Excess-qp GR-Noise

GR - NoisePhoton Noise

Optical efficiency: 48%

arXiv:1306.4238