On-chip SQUID measurements in the presence of high magnetic fields

Chen, Lei; Wernsdorfer, Wolfgang; Lampropoulos, Christos; Christou, George; Chiorescu, Irinel

doi:10.1088/0957-4484/21/40/405504

Cited by 37 publications

(42 citation statements)

References 25 publications

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“…Such a hybrid implementation with phosphorus donor electron spins could be challenging due to the large magnetic fields that are required, which could drive the Josephson junctions of the superconducting qubit normal, although junctions have been shown to operate successfully in fields up to 7 T [44]. One alternative is to utilize a different donor, like bismuth, with a large enough zero-field splitting to enable low-field measurements [45].…”

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confidence: 99%

Coherent Rabi Dynamics of a Superradiant Spin Ensemble in a Microwave Cavity

et al. 2017

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We achieve the strong-coupling regime between an ensemble of phosphorus donor spins in a highly enriched 28 Si crystal and a 3D dielectric resonator. Spins are polarized beyond Boltzmann equilibrium using spin-selective optical excitation of the no-phonon bound exciton transition resulting in N ¼ 3.6 × 10 13 unpaired spins in the ensemble. We observe a normal mode splitting of the spin-ensemble-cavity polariton resonances of 2g ffiffiffiffi N p ¼ 580 kHz (where each spin is coupled with strength g) in a cavity with a quality factor of 75 000 ( γ ≪ κ ≈ 60 kHz, where γ and κ are the spin dephasing and cavity loss rates, respectively). The spin ensemble has a long dephasing time (T Ã 2 ¼ 9 μs) providing a wide window for viewing the dynamics of the coupled spin-ensemble-cavity system. The free-induction decay shows up to a dozen collapses and revivals revealing a coherent exchange of excitations between the superradiant state of the spin ensemble and the cavity at the rate g ffiffiffiffi N p. The ensemble is found to evolve as a single large pseudospin according to the Tavis-Cummings model due to minimal inhomogeneous broadening and uniform spin-cavity coupling. We demonstrate independent control of the total spin and the initial Z projection of the psuedospin using optical excitation and microwave manipulation, respectively. We vary the microwave excitation power to rotate the pseudospin on the Bloch sphere and observe a long delay in the onset of the superradiant emission as the pseudospin approaches full inversion. This delay is accompanied by an abrupt π-phase shift in the peusdospin microwave emission. The scaling of this delay with the initial angle and the sudden phase shift are explained by the Tavis-Cummings model.

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confidence: 99%

Coherent Rabi Dynamics of a Superradiant Spin Ensemble in a Microwave Cavity

et al. 2017

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“…The SQUIDs share a common ground (sketched as a white rectangle). Each SQUID has one I − V line shown in green for clarity in their narrowest region.can work under in-plane magnetic fields in the range of ∼Tesla [28][29][30] .Using this setup, we successfully measured the resonance signal of Gd 3+ S = 7/2 ions diluted in a CaWO 4 single crystal with a concentration of 0.05%. Moreover, the resonance is between the first and third excited states at T = 0.5 K, demonstrating high sensitivity for applications in spin control in multi-level quantum system.…”

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confidence: 99%

Sensitive spin detection using an on-chip SQUID-waveguide resonator

Yue

Chen

Barreda

et al. 2017

Applied Physics Letters

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Precise detection of spin resonance is of paramount importance to achieve coherent spin control in quantum computing. We present a novel setup for spin resonance measurements, which uses a dc-SQUID flux detector coupled to an antenna from a coplanar waveguide. The SQUID and the waveguide are fabricated from 20 nm Nb thin film, allowing high magnetic field operation with the field applied parallel to the chip. We observe a resonance signal between the first and third excited states of Gd spins S = 7/2 in a CaWO 4 crystal, relevant for state control in multi-level systems.Solid state spin-based qubits are studied for quantum computing due to their relatively long coherence time 1,2 . Typical implementations of these qubits are molecule-based magnets 3-6 , nitrogen-vacancy (NV) centers in diamond 7 and quantum spins in crystals 8-11 . These spin-based qubits are designed such that the spins are well separated in the crystal, leading to an increased decoherence time due to weak spin dipolar interactions.Among the rare-earth ions, S-state lanthanide ions doped in a crystal have a rich energy level structure due to their large spin. Multi-level systems are promising for implementing few-qubits algorithms 12 or as quantum memories [13][14][15][16] . For quantum technology applications, a higher sensitivity electron spin resonance (ESR) measurement is needed to be able to manipulate spins in mesoscopic crystals placed on superconducting chips [17][18][19][20][21] .Compared to other ultra-high sensitivity ESR measurements 22,23 , the use of Josephson junctions can increase significantly the spatial resolution of the magnetic detection while allowing an on-chip implementation. For instance, the magnetic signal of one nanoparticle is detectable if placed on the junction of a micrometer sized superconducting quantum interference device (micro-SQUID) 24 . We present a novel setup for ESR measurements, which combines the high spin sensitivity of an on-chip micro-SQUID and the flexibility of a coplanar waveguide for microwave excitation. Different dc-SQUID implementations were also used to detect molecular 25,26 and diluted 27 spins. In our case, the coupling of the two devices generates a cavity effect, which amplifies the microwave power seen by the spins. When using micro-SQUIDs, the samples are positioned close to their loop for increased sensitivity since the device a) Electronic mail: gy10c@my.fsu.edu b) Electronic mail: ic@magnet.fsu. edu FIG. 1. (color online) Scanning electron micrograph of the device and of the micro-SQUID (inset). The darker (blue) area is the coplanar waveguide with the two Ω-loop shortcircuits between the central line and the lateral ground planes. The microwave excitation is depicted by the curvy arrow and an in-plane field B0 is generated by an external coil. The SQUIDs share a common ground (sketched as a white rectangle). Each SQUID has one I − V line shown in green for clarity in their narrowest region.can work under in-plane magnetic fields in the range of ∼Tesla [28][29][30] .Using this s...

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“…The planar Nb nano-SQUID in Fig. 1(b) do have a large intrinsic flux noise because of its large inductance, but can be operated in a high parallel magnetic field12. However, the system noise of 28 μФ 0 /Hz 1/2 has been limited by the room-temperature amplifier and not reached its intrinsic noise level yet.…”

Section: Resultsmentioning

confidence: 99%

“…Because the nano-SQUID can be directly coupled to a small sample in the magnetic field12131415, it has made a great contribution to the field of nano-magnetism16171819. Recently, it was demonstrated that a nano-SQUID can be integrated on the tip of a scanning SQUID microscope to perform high-resolution imaging over a sample surface2021222324.…”

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Meissner effect measurement of single indium particle using a customized on-chip nano-scale superconducting quantum interference device system

Chen

Wang

et al. 2017

Sci Rep

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As many emergent phenomena of superconductivity appear on a smaller scale and at lower dimension, commercial magnetic property measurement systems (MPMSs) no longer provide the sensitivity necessary to study the Meissner effect of small superconductors. The nano-scale superconducting quantum interference device (nano-SQUID) is considered one of the most sensitive magnetic sensors for the magnetic characterization of mesoscopic or microscopic samples. Here, we develop a customized on-chip nano-SQUID measurement system based on a pulsed current biasing method. The noise performance of our system is approximately 4.6 × 10−17 emu/Hz1/2, representing an improvement of 9 orders of magnitude compared with that of a commercial MPMS (~10−8 emu/Hz1/2). Furthermore, we demonstrate the measurement of the Meissner effect of a single indium (In) particle (of 47 μm in diameter) using our on-chip nano-SQUID system. The system enables the observation of the prompt superconducting transition of the Meissner effect of a single In particle, thereby providing more accurate characterization of the critical field Hc and temperature Tc. In addition, the retrapping field Hre as a function of temperature T of single In particle shows disparate behavior from that of a large ensemble.

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On-chip SQUID measurements in the presence of high magnetic fields

Cited by 37 publications

References 25 publications

Coherent Rabi Dynamics of a Superradiant Spin Ensemble in a Microwave Cavity

Coherent Rabi Dynamics of a Superradiant Spin Ensemble in a Microwave Cavity

Sensitive spin detection using an on-chip SQUID-waveguide resonator

Meissner effect measurement of single indium particle using a customized on-chip nano-scale superconducting quantum interference device system

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