On-and-off chip cooling of a Coulomb blockade thermometer down to 2.8 mK

Palma, Mario; Scheller, Christian; Maradan, Dario; Feshchenko, A. V.; Meschke, Matthias; Zumbühl, Dominik M.

doi:10.1063/1.5002565

Cited by 31 publications

(47 citation statements)

References 37 publications

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“…We compare our data with prior work in the inset of Fig. 3a and note that our results are comparable to [23] where T e = 2.8 mK was achieved by a combination of on-and off-chip Cu nuclear cooling stages.…”

Section: On-chip Nuclear Magnetic Coolingsupporting

confidence: 79%

“…We evaluate the performance of electroplated In as an on-chip electron refrigerant by considering the nuclear heat capacity integrated on-chip per unit area, α = αn/A and use α /κ as a figure of merit containing both the material parameters and the device geometry. Our device features α /κ In = 250 µW/(m 2 KT 2 ), which is a factor of 3300 increase compared to α /κ Cu = 0.076 µW/(m 2 KT 2 ) implemented in [23], clearly substantiating the merits of our approach.…”

Section: On-chip Nuclear Magnetic Coolingsupporting

confidence: 65%

“…4),Q leak = a|Ḃ| +Q 0 with a = 18 pW/(mT s −1 ) andQ 0 = 0.18 fW per island. Notably, the largest measured heat leak per island is 108 fW corresponding to a total heat leak of 60 pW for the chip, exceeding earlier reported values in similar experiments [23,24]. The linearQ leak (Ḃ) is in striking contrast with observations on macroscopically large nuclear cooling stages, where eddy currents in the bulk refrigerant lead to aQ leak ∝Ḃ 2 [21].…”

Section: On-chip Nuclear Magnetic Coolingmentioning

confidence: 55%

“…In addition, the experimental implementation should allow for a large n and B 2 i /T 2 n,i ratio for efficient cooling and long cold time. Thus far, copper (Cu) was the sole material utilized for the nuclear cooling of nanoelectronics [22][23][24]. Naturally occuring Cu nuclei have a spin of 3/2 yielding arXiv:1811.03034v1 [cond-mat.mes-hall] 7 Nov 2018 α Cu = 3.22 µJKT −2 mol −1 [21].…”

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confidence: 99%

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Indium as a High-Cooling-Power Nuclear Refrigerant for Quantum Nanoelectronics

2019

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The frontiers of quantum electronics have been linked to the discovery of new refrigeration methods since the discovery of superconductivity at a temperature around 4 K, enabled by the liquefaction of helium. Presently, nanoelectronic devices typically reach electron temperatures around 10 mK to 100 mK by commercially available dilution refrigerators. This led to discoveries such as the quantum Hall effect and new technologies like superconducting and semiconductor quantum bits. However, cooling electrons via the encompassing lattice vibrations, or phonons, becomes inefficient at low temperatures. Further progress towards lower temperatures requires new cooling methods for electrons on the nanoscale, such as direct cooling with nuclear spins, which themselves can be brought to microkelvin temperatures by adiabatic demagnetization. Here, we introduce indium as a nuclear refrigerant for nanoelectronics and demonstrate that solely on-chip cooling of electrons is possible down to a record low temperature of 3.2 ± 0.1 mK in an unmodified dilution refrigerator.Quantum electronics relies on the precise control of electronic states in nanostructures, which is possible if the energy level separation is much higher than the thermal energy k B T . Thus, the efficient cooling of electrons is vital for solid state nanoelectronics and is an important design consideration for existing scalable quantum technologies. Access to novel states of matter such as electron-nuclear ferromagnets [1-3], non-Abelian anyons in fractional quantum Hall states [4,5], topological insulators [6] or exotic superconductivity [7-9] requires further progress in the cooling of nanoelectronics, approaching the µK regime.Typical electron temperatures of the order of 10 mK are accessible in semiconductor and metallic nanostructures by mounting the chip containing the devices on an insulating substrate cooled by commercially available dilution refrigerators. The lowest achievable electron temperature is limited by the heat transferred from the electrons at a temperature of T e to phonons at a temperature of T p . The heat flow between conduction electrons and phonons in a metallic volume V isQ ep = ΣV T 5 e order of 10 9 WK −5 m −3 [10,11]. A residual heat leak oḟ Q leak = 10 aW to a well-shielded nanostructure [12] with V = 1 µm 3 then yields T e ≈ 25 mK even as T p approaches zero. Increasing the coupling volume V by electrodeposition of thick metal films and improving thermalization by liquid helium immersion cells led to T e ≈ 4 mK [13][14][15] in specially built dilution refrigerators.The key to reduce the electron temperature further thus involves coupling the electron system to a cold bath without the necessity of heat transport via phonons. This can be achieved by nuclear magnetic cooling. In the limit of small Zeeman splitting compared to k B T n , the magnetization of the nuclear spin system is M ∝ B/T n at a magnetic field of B and a temperature of T n . T n can be reduced by adiabatically lowering the magnetic field from B i to B f . In the ab...

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Section: On-chip Nuclear Magnetic Coolingsupporting

confidence: 79%

Section: On-chip Nuclear Magnetic Coolingsupporting

confidence: 65%

Section: On-chip Nuclear Magnetic Coolingmentioning

confidence: 55%

mentioning

confidence: 99%

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Indium as a High-Cooling-Power Nuclear Refrigerant for Quantum Nanoelectronics

2019

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“…The non-Markovian behaviour becomes pertinent when memory times are enhanced as it occurs by the modern developments of reaching sub-millikelvin temperatures even for electronic nanostructures [19][20][21] and by the design and discovery of strongly correlated materials. The latter exhibit collective responses to local excitations that naturally extend correlations in space and time, and thus the memory time.…”

Section: Introductionmentioning

confidence: 99%

Coherent backaction between spins and an electronic bath: Non-Markovian dynamics and low-temperature quantum thermodynamic electron cooling

et al. 2019

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We provide a general analytical framework for calculating the dynamics of a spin system in contact with a bath beyond the Markov approximation. The approach is based on a systematic expansion of the Nakashima-Zwanzig master equation in the weak-coupling limit but makes no assumption on the time dynamics and includes all quantum coherent memory effects leading to non-Markovian dynamics. Our results describe, for the free induction decay, the full time range from the non-Markovian dynamics at short times, to the well-known exponential thermal decay at long times. We provide full analytic results for the entire time range using a bath of itinerant electrons as an archetype for universal quantum fluctuations. Furthermore, we propose a quantum thermodynamic scheme to employ the temperature insensitivity of the non-Markovian decay to transport heat out of the electron system and thus, by repeated re-initialisation of a cluster of spins, to efficiently cool the electrons at very low temperatures.

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On-Chip Demagnetisation Cooling of a High Capacitance CBT

Jones

2020

Springer Theses

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On-and-off chip cooling of a Coulomb blockade thermometer down to 2.8 mK

Cited by 31 publications

References 37 publications

Indium as a High-Cooling-Power Nuclear Refrigerant for Quantum Nanoelectronics

Indium as a High-Cooling-Power Nuclear Refrigerant for Quantum Nanoelectronics

Coherent backaction between spins and an electronic bath: Non-Markovian dynamics and low-temperature quantum thermodynamic electron cooling

On-Chip Demagnetisation Cooling of a High Capacitance CBT

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