This article mainly focuses on one of the important phenomena in the quantum realm called entanglement. It is clear that entanglement created due to the nonlinearity property has been arisen by some different methods. This study in contrast uses a unique approach in which a cryogenic low noise amplifier is designed and using the transistor nonlinearity effect (third-order nonlinearity) entangled microwave photons are created. It is supposed that the low noise amplifier contains two coupled oscillators resonating with different frequencies. The mentioned oscillators are coupled to each other through the gate-drain capacitor and nonlinear transconductance as an important factor by which the entangled microwave photons are strongly manipulated. For entanglement analysis, the Hamiltonian of the system is initially derived, then using the dynamic equation of motion of the designed amplifier the oscillator's number of photons and also the phase sensitive cross-correlation factor are calculated in Fourier domain to calculate the entanglement metric. As a main conclusion, the study shows that the designed low noise amplifier using nonlinearity of the transistor has the ability to generate the entangled microwave photons at very low intrinsic transconductance and more importantly when the noise figure is strongly minimized. Additionally, a cryogenic low noise amplifier is designed and simulated to verify that it is possible to achieve an ultra-low noise figure by which the probability of the generation of the entangled microwave photons is increased.
General quantum restrictions on the noise performance of linear transistor amplifiers are used to identify the region in parameter space where the quantum-limited performance is achievable and to construct a practical procedure for approaching it experimentally using only the knowledge of directly measurable quantities: the gain, (differential) conductance and the output noise. A specific example of resonant barrier transistors is discussed.
California Institute of Technology（加州理工学院）；National Institute of Standards and Technology（美国国家标准与技术研究院）；University of Colorado, Boulder（科罗拉多大学博尔德分校）；University of Milano-Bicocca（米兰比可卡大学）
This study focuses on generating and manipulating squeezed states with two external oscillators coupled by an InP HEMT transistor operating at cryogenic temperatures. First, the small-signal nonlinear model of the transistor at high frequency at 5 K is analyzed using quantum theory, and the related Lagrangian is theoretically derived. Subsequently, the total quantum Hamiltonian of the system is derived using Legendre transformation. The Hamiltonian of the system includes linear and nonlinear terms, by which the effects on the time evolution of the states are studied. The main result shows that…
We present a cryogenic microwave noise source with a characteristic impedance of 50 $Ω$, which can be installed in a coaxial line of a cryostat. The bath temperature of the noise source is continuously variable between 0.1 K and 5 K without causing significant back-action heating on the sample space. As a proof-of-concept experiment, we perform Y-factor measurements of an amplifier cascade that includes a traveling wave parametric amplifier and a commercial high electron mobility transistor amplifier. We observe system noise temperatures as low as $680^{+20}_{-200}$ mK at 5.7 GHz corresponding…
An ideal preamplifier for qubit measurement must not only provide high gain and near quantum-limited noise performance, but also isolate the delicate quantum circuit from noisy downstream measurement stages while producing negligible backaction. Here we use a Superconducting Low-inductance Undulatory Galvanometer (SLUG) microwave amplifier to read out a superconducting transmon qubit, and we characterize both reverse isolation and measurement backaction of the SLUG. For appropriate dc bias, the SLUG achieves reverse isolation that is better than that of a commercial cryogenic isolator. Moreove…
Nonlinear amplifiers such as the transistor are ubiquitous in classical technology, but their quantum analogues are not well understood. We introduce a class of nonlinear amplifiers that amplify any normal operator and add only a half-quantum of vacuum noise at the output. In the large-gain limit, when used in conjunction with a noisy linear detector, these amplifiers implement ideal measurements of the normal operator.
A three-terminal device, able to control the heat currents flowing through it, is known as a quantum thermal transistor whenever it amplifies two output currents as a response to the external source acting on its third terminal. Several efforts have been proposed in the direction of addressing different engineering options of the configuration of the system. Here, we adhere to the scheme in which such a device is implemented as a three-qubit system that interacts with three separate thermal baths. However, another interesting direction is how to engineer the thermal reservoirs to magnify the c…
Amplifiers are ubiquitous in electronics and play a fundamental role in a wide range of scientific measurements. From a user's perspective, an ideal amplifier has very low noise, operates over a broad frequency range, and has a high dynamic range - it is capable of handling strong signals with little distortion. Unfortunately, it is difficult to obtain all of these characteristics simultaneously. For example, modern transistor amplifiers offer multi-octave bandwidths and excellent dynamic range. However, their noise remains far above the fundamental limit set by the uncertainty principle of qu…
Statistical evaluation of 571 GaAs quantum point contact transistors showing the 0.7 anomaly in quantized conductance using millikelvin cryogenic on-chip multiplexing
Revisiting Thermal Scalability for Large-Scale Superconducting Quantum Systems
Faculty of Information Science and Electrical Engineering, Kyushu University（九州大学信息科学与电气工程学院）；Secure System Platform Research Laboratories, NEC Corporation（NEC公司安全系统平台研究实验室）；Global Research and Development Center for Business by Quantum-AI Technology (G-QuAT), National Institute of Advanced Industrial Science and Technology (AIST)（国立产业技术综合研究所量子AI技术商业研发中心）；Advanced Technology Center, National Astronomical Observatory of Japan (NAOJ)（日本国立天文台先进技术中心）；Graduate University for Advanced Studies (SOKENDAI)（综合研究大学院大学）
We investigate the effect of a degenerate optical parametric amplifier (OPA) placed inside an optomechanical cavity on the steady-state entanglement of two cavity modes, which jointly interact with a mechanical resonator. Two cavity modes are respectively driven at the red and blue sideband associated with the mechanical resonator, which generates entanglement between them in the limit of resolved sideband. The OPA gives rise to single-mode squeezing of the cavity fields, which results in significant improvement of the two-mode entanglement. It is found that an optimal nonlinear gain of the OP…
Most microwave readout architectures in quantum computing or sensing rely on a semiconductor amplifier at 4 K, typically a high-electron mobility transistor (HEMT). Despite its remarkable noise performance, a conventional HEMT dissipates several milliwatts of power, posing a practical challenge to scale up the number of qubits or sensors addressed in these architectures. As an alternative, we present an amplification chain consisting of a kinetic-inductance traveling-wave parametric amplifier (KI-TWPA) placed at 4 K, followed by a HEMT placed at 70 K, and demonstrate a chain-added noise $T_Σ= …
A scaled-up quantum computer will require a highly efficient control interface that autonomously manipulates and reads out large numbers of qubits, which for solid-state implementations are usually held at millikelvin (mK) temperatures. Advanced CMOS technology, tightly integrated with the quantum system, would be ideal for implementing such a control interface but is generally discounted on the basis of its power dissipation that leads to heating of the fragile qubits. Here, we demonstrate an ultra low power, CMOS-based quantum control platform that takes digital commands as input and generat…
We have fabricated a wide-bandwidth, high dynamic range, low-noise cryogenic amplifier based on a superconducting kinetic inductance traveling-wave device. The device was made from NbTiN and consisted of a long, coplanar waveguide on a silicon chip. By adding a DC current and an RF pump tone we are able to generate parametric amplification using three-wave mixing. The devices exhibit gain of more than 15 dB across an instantaneous bandwidth from 4 to 8 GHz. The total usable gain bandwidth, including both sides of the signal-idler gain region, is more than 6 GHz. The noise referred to the input…
Thermal Nyquist noise fluctuations of high-$Q$ Bulk Acoustic Wave (BAW) cavities have been observed at cryogenic temperatures with a DC Superconducting Quantum Interference Device (SQUID) amplifier. High $Q$ modes with bandwidths of few tens of milliHz produce thermal fluctuations with a Signal-To-Noise ratio of up to 23dB. The estimated effective temperature from the Nyquist noise is in good agreement with the physical temperature of the device, confirming the validity of the equivalent circuit model and the non-existence of any excess resonator self-noise. The measurements also confirm that …
Fault-tolerant spin-based quantum computers will require fast and accurate qubit readout. This can be achieved using radio-frequency reflectometry given sufficient sensitivity to the change in quantum capacitance associated with the qubit states. Here, we demonstrate a 23-fold improvement in capacitance sensitivity by supplementing a cryogenic semiconductor amplifier with a SQUID preamplifier. The SQUID amplifier operates at a frequency near 200 MHz and achieves a noise temperature below 600 mK when integrated into a reflectometry circuit, which is within a factor 120 of the quantum limit. It …
