Periodic Reporting for period 3 - SUPERGALAX (Highly sensitive detection of single microwave photons with coherent quantum network of superconducting qubits for searching galactic axions)
Periodo di rendicontazione: 2023-01-01 al 2023-12-31
The overall objectives of the project are to develop and realize conceptually novel and practical quantum limited superconducting qubits network (SQN) detector capable to reveal single microwave (MW) photons for a photon frequency of ~10 GHz (with the energy 32000 times less than the energy of infrared visible photons) with a view to apply it to a search for galactic axions –cold dark matter candidates- by means of a “haloscopes”- the laboratory converter of axions to MW photons.
The context objectives of the project are:
-to develop a single MW photon detector based on moderate size networks of interacting superconducting qubits;
-to develop an heralded microwave single photon source based on the Traveling Wave Josephson Parametric Amplifier (TWJPA);
-to develop the single photon SQN detector integrated with the single photon source;
-experimental study of feasibility of the single photon SQN detector for the “haloscope” type of axion searching.
The context objectives of the project are:
-to develop a single MW photon detector based on moderate size networks of interacting superconducting qubits;
-to develop an heralded microwave single photon source based on the Traveling Wave Josephson Parametric Amplifier (TWJPA);
-to develop the single photon SQN detector integrated with the single photon source;
-experimental study of feasibility of the single photon SQN detector for the “haloscope” type of axion searching.
Superconducting qubit network (SQN) detectors with different geometries and based on 5 and 10 flux qubits, 8 and 25 transmons have been designed, fabricated and tested.
The SQNs with 8 transmons coupled to the coplanar waveguide were used to experimental study of the waveguide induced long-range interaction between qubits (Fig. 1). The qubits were tuned to a common resonance frequency at 7.898 GHz. Spectroscopic microwave (MW) test measurements (Fig. 2) have given an experimental evidence for a stable collective quantum state in the SQN up to 8 qubits. Time resolved experiments showed reduced group velocities of down to a factor of about 1500 smaller than in vacuum.
We have elaborated the theory of an SQN interacting with a weak MW radiation. The Heisenberg limit of sensitivity is reached in the presence of a strong long-range interaction between qubits. The interaction of single MW photons with an array of transmon in a waveguide cavity resonator has been theoretically investigated.
The coherent collective quantum states have been theoretically studied in disordered SQNs coupled to a low-dissipative resonator and a transmission line. An inductive coupling of SQN to a low-dissipative resonator provides an effective long-range interaction between all qubits. Coupling of an SQN to the transmission line allows one to experimentally access the temporal correlation function of equilibrium/non-equilibrium total polarization (Fig. 3). The collective quantum dynamics occurring in SQNs in presence of a spread of individual qubit frequencies has been studied theoretically. An amplitude of the main resonance drastically increases as the interaction overcomes the disorder, and the collective state is formed. In the presence of a weak non-resonant photon field, the positions of resonances depend on the number of photons, i.e. the collective ac Stark effect is obtained (Fig.4).
The heralded single MW photon source based on Josephson Traveling Wave Parametric Amplifier (JTWPA)-was designed and fabricated (Fig. 5). Measurements of the correlated signals at the output of the JTWPA were performed at T=45 mK.
T-type three terminal SQNs with 10 c-shunted flux qubits have been fabricated (Fig. 6). The first-tone S21 was measure as a function of frequency in the presence of the second-tone (ST) signal applied to port 3. A shift of the position of the resonant transmission dip as a function of the amplitude of the ST signal was observed (Fig.7a). The power at which this shift took place depended on the ST signal frequency (Fig. 7b). Experimental results are in a good agreement with the model based on a non-linear multiphoton interaction between second-tone MW signal and a qubit system of the SQN (Fig.7b). The detector sensitivity of our SQN device is suitable to count a few photons biasing the resonator between port 1 and port 2 at frequency of 7.743 GHz.
Sikivie’s Haloscope at the National Laboratories of INFN in Frascati has been successfully tested and operated at 30 mK.
The Workshop "Searching for Galactic Axions and Superconducting Devices with Quantum Efficiency" have been organised on October 25-29,2021 with the help of SUPERGALAX consortium. Special Session on Quantum Detection in the framework of the WOLTE14 workshop has been organized. The SUPERGALAX activity has been presented on the ASC 22 and on the EUCAS 23 conferences. Several scientific seminars hosted the talks about SUPERGARAX activities have been periodically hold.
The SQNs with 8 transmons coupled to the coplanar waveguide were used to experimental study of the waveguide induced long-range interaction between qubits (Fig. 1). The qubits were tuned to a common resonance frequency at 7.898 GHz. Spectroscopic microwave (MW) test measurements (Fig. 2) have given an experimental evidence for a stable collective quantum state in the SQN up to 8 qubits. Time resolved experiments showed reduced group velocities of down to a factor of about 1500 smaller than in vacuum.
We have elaborated the theory of an SQN interacting with a weak MW radiation. The Heisenberg limit of sensitivity is reached in the presence of a strong long-range interaction between qubits. The interaction of single MW photons with an array of transmon in a waveguide cavity resonator has been theoretically investigated.
The coherent collective quantum states have been theoretically studied in disordered SQNs coupled to a low-dissipative resonator and a transmission line. An inductive coupling of SQN to a low-dissipative resonator provides an effective long-range interaction between all qubits. Coupling of an SQN to the transmission line allows one to experimentally access the temporal correlation function of equilibrium/non-equilibrium total polarization (Fig. 3). The collective quantum dynamics occurring in SQNs in presence of a spread of individual qubit frequencies has been studied theoretically. An amplitude of the main resonance drastically increases as the interaction overcomes the disorder, and the collective state is formed. In the presence of a weak non-resonant photon field, the positions of resonances depend on the number of photons, i.e. the collective ac Stark effect is obtained (Fig.4).
The heralded single MW photon source based on Josephson Traveling Wave Parametric Amplifier (JTWPA)-was designed and fabricated (Fig. 5). Measurements of the correlated signals at the output of the JTWPA were performed at T=45 mK.
T-type three terminal SQNs with 10 c-shunted flux qubits have been fabricated (Fig. 6). The first-tone S21 was measure as a function of frequency in the presence of the second-tone (ST) signal applied to port 3. A shift of the position of the resonant transmission dip as a function of the amplitude of the ST signal was observed (Fig.7a). The power at which this shift took place depended on the ST signal frequency (Fig. 7b). Experimental results are in a good agreement with the model based on a non-linear multiphoton interaction between second-tone MW signal and a qubit system of the SQN (Fig.7b). The detector sensitivity of our SQN device is suitable to count a few photons biasing the resonator between port 1 and port 2 at frequency of 7.743 GHz.
Sikivie’s Haloscope at the National Laboratories of INFN in Frascati has been successfully tested and operated at 30 mK.
The Workshop "Searching for Galactic Axions and Superconducting Devices with Quantum Efficiency" have been organised on October 25-29,2021 with the help of SUPERGALAX consortium. Special Session on Quantum Detection in the framework of the WOLTE14 workshop has been organized. The SUPERGALAX activity has been presented on the ASC 22 and on the EUCAS 23 conferences. Several scientific seminars hosted the talks about SUPERGARAX activities have been periodically hold.
Proposed detection principle based on interacting superconducting qubit networks (SQNs) will outperform state-of-the-art of currently existing single qubit detectors in:
- high efficiency of detection of single microwave (MW) photons.
- in sensitivity up to the Heisenberg limit
- a quantum non-demolition measurement and probe spatial correlations of photon states.
- detecting the signal even against the background of strong local ambient noise.
Expected results:
- design and fabrication both of SQNs detector and of an heralded single MW photon source based on Josephson Travelling Wave Parametric Amplifier (JTWPA);
-a theoretical study of temporal and spatial correlations of single photons interacting with an SQN; theory of a Heisenberg limited superconducting quantum detector; theory of the collective AC Stark effect.
-experimental evidences of the collective states in SQN; experimental detection of low MW power signals by SQNs
The potential impact of the project is
-technology: Design and fabrication both of a SQN detector and of an JTWPA with a large number (up to 900) Josephson junctions;
-metrology: SQN single MW photon detector will be considered as an indispensable tool for test measurements of innovative solid-state MW single photon sources. An heralded JTWPA single MW photon source will be useful to calibrate novel MW quantum detectors;
-quantum sensing: SQN single MW photon detector together with the heralded JTWPA single MW photon source will permit to apply the MW quantum illumination protocol;
-medicine and biology: Devices developer in the project could benefit for the use of imaging techniques on biological samples that exploits low flux regimes in the MW;
-quantum computation and communication: Devices developed in the project could extend the range of useful wavelengths up to MW for Quantum Key Distribution protocols;
- MW quantum photonic circuits: High fidelity of the developed JTWPA source will permit to realize photonic circuits with synchronized multiple single photon sources;
- quantum simulators: SQN detector with quantum limit sensitivity is an essential device for quantum modelling with MW solid-state circuits, for ultrasensitive analysis of MW components and non-classical photon states;
- theoretical physics: Theory for modelling of large networks of strongly coupled superconducting qubits
- fundamental physics knowledge: The novel SQN detector will be employed in the experimental search of axions.
-education in quantum technology: Seminars in the Bochum University (Germany) and in the Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon (Republic of Korea). Bachelor and master student’s research activity.
-social impact: Financial support of 5 PhD fellow researchers.
- high efficiency of detection of single microwave (MW) photons.
- in sensitivity up to the Heisenberg limit
- a quantum non-demolition measurement and probe spatial correlations of photon states.
- detecting the signal even against the background of strong local ambient noise.
Expected results:
- design and fabrication both of SQNs detector and of an heralded single MW photon source based on Josephson Travelling Wave Parametric Amplifier (JTWPA);
-a theoretical study of temporal and spatial correlations of single photons interacting with an SQN; theory of a Heisenberg limited superconducting quantum detector; theory of the collective AC Stark effect.
-experimental evidences of the collective states in SQN; experimental detection of low MW power signals by SQNs
The potential impact of the project is
-technology: Design and fabrication both of a SQN detector and of an JTWPA with a large number (up to 900) Josephson junctions;
-metrology: SQN single MW photon detector will be considered as an indispensable tool for test measurements of innovative solid-state MW single photon sources. An heralded JTWPA single MW photon source will be useful to calibrate novel MW quantum detectors;
-quantum sensing: SQN single MW photon detector together with the heralded JTWPA single MW photon source will permit to apply the MW quantum illumination protocol;
-medicine and biology: Devices developer in the project could benefit for the use of imaging techniques on biological samples that exploits low flux regimes in the MW;
-quantum computation and communication: Devices developed in the project could extend the range of useful wavelengths up to MW for Quantum Key Distribution protocols;
- MW quantum photonic circuits: High fidelity of the developed JTWPA source will permit to realize photonic circuits with synchronized multiple single photon sources;
- quantum simulators: SQN detector with quantum limit sensitivity is an essential device for quantum modelling with MW solid-state circuits, for ultrasensitive analysis of MW components and non-classical photon states;
- theoretical physics: Theory for modelling of large networks of strongly coupled superconducting qubits
- fundamental physics knowledge: The novel SQN detector will be employed in the experimental search of axions.
-education in quantum technology: Seminars in the Bochum University (Germany) and in the Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon (Republic of Korea). Bachelor and master student’s research activity.
-social impact: Financial support of 5 PhD fellow researchers.