Quantum simulation of clustered photosynthetic light harvesting in a superconducting quantum circuit

  1. Ming-Jie Tao,
  2. Ming Hua,
  3. Qing Ai,
  4. and Fu-Guo Deng
We propose a scheme to simulate the exciton energy transfer (EET) of photosynthetic complexes in a quantum superconducting circuit system. Our system is composed of two pairs of superconducting
charge qubits coupled to two separated high-Q superconducting transmission line resonators (TLRs) connected by a capacitance. When the frequencies of the qubits are largely detuned with those of the TLRs, we simulate the process of the EET from the first qubit to the fourth qubit. By tuning the couplings between the qubits and the TLRs, and the coupling between the two TLRs, we can modify the effective coupling strengths between the qubits and thus demonstrate the geometric effects on the EET. It is shown that a moderate clustered geometry supports optimal EET by using exciton delocalization and energy matching condition. And the population loss during the EET has been trapped in the two TLRs.

Quantum network for information processing on superconducting qubits with dark microwave photons

  1. Ming Hua,
  2. Ming-Jie Tao,
  3. and Fu-Guo Deng
We present two one-step schemes to generate the Bell state and construct the controlled-phase gate deterministically on remote transmon qutrits trapped in different resonators connected
by a superconducting transmission line for a quantum network. They are implemented with coherent evolutions of the entire system in the all-resonance regime assisted by the dark microwave photons which are robust against the transmission line loss. Different from previous works in other quantum systems for a quantum network, the present proposals do not require classical pulses and ancillary qubits. Our simulations with feasible parameters show that the fidelities of both these schemes exceed 99% which is beyond the fault-tolerant threshold for quantum communication.

One-step implementation of entanglement generation on microwave photons in distant 1D superconducting resonators

  1. Ming Hua,
  2. Ming-Jie Tao,
  3. and Fu-Guo Deng
We present a scalable quantum-bus-based device for generating the entanglement on microwave photons (MPs) in distant superconducting resonators (SRs). Different from the processors
in previous works with some resonators coupled to a superconducting qubit (SQ), our device is composed of some 1D SRs rj which are coupled to the quantum bus (another common resonator R) in its different positions simply, assisted by superconducting quantum interferometer devices. By using the technique for catching and releasing a MP state in a 1D SR, it can work as an entanglement generator or a node in quantum communication. To demonstrate the performance of this device, we propose a one-step scheme to generate high-fidelity Bell states on MPs in two distant SRs. It works in the dispersive regime of rj and R, which enables us to extend it to generate high-fidelity multi-Bell states on different resonator pairs simultaneously.

Efficient generation of NOON states on two microwave-photon resonators

  1. Ming Hua,
  2. Ming-Jie Tao,
  3. and Fu-Guo Deng
We present an efficient scheme for the generation of NOON states of photons in circuit QED assisted by a superconducting charge qutrit. It is completed with two kinds of manipulations,
that is, the resonant operation on the qutrit and the resonator, and the single-qubit operation on the qutrit, and they both are high-fidelity operations. Compared with the one by a superconducting transmon qutrit proposed by Su et al. (Sci. Rep. 4, 3898 (2014)), our scheme does not require to maintain the qutrit in the third excited state with a long time, which relaxes the difficulty of its implementation in experiment. Moreover, the level anharmonicity of a charge qutrit is larger and it is better for us to tune the different transitions of the charge qutrit resonant to the resonator, which makes our scheme faster than others.

Quantum state transfer and controlled-phase gate on 1D superconducting resonators assisted by a quantum bus

  1. Ming Hua,
  2. Ming-Jie Tao,
  3. and Fu-Guo Deng
We propose a quantum processor for the scalable quantum computation based on microwave photons in 1D superconducting resonators. Different from the previous processors which are composed
of some resonators coupled to a superconducting qubit, our processor is composed of some resonators ri and a common resonator R acting as a quantum bus, which makes it have the capability of integrating more resonators simply by coupling them to the bus R in different positions. R is coupled to only one transmon qutrit, and the coupling strengths between ri and R can be fully tuned. To show the processor can be used to achieve universal quantum computation effectively, we present a scheme to complete the high-fidelity quantum state transfer between two microwave-photon resonators and another one for the high-fidelity controlled-phase gate on them.

Fast universal quantum gates on microwave photons with all-resonance operations in circuit QED

  1. Ming Hua,
  2. Ming-Jie Tao,
  3. and Fu-Guo Deng
Quantum stark effect on superconducting qubits in circuit quantum electrodynamics (QED) has been used to construct universal quantum entangling gates on superconducting resonators in
previous works. It is a second-order coupling effect between the resonator and the qubit in the dispersive regime, which leads to a long-time state-selective rotation on the qubit. Here, we use the quantum resonance operations to construct the fast universal quantum gates on superconducting resonators in a microwave-photon quantum processor composed of some superconducting resonators coupled to a superconducting transmon, phase, or Xmon qutrit assisted by circuit QED in the dispersive regime, including the controlled-phase (c-phase) gate on two microwave-photon resonators and the controlled-controlled phase (cc-phase) gates on three microwave-photon resonators. Compared with previous works, our universal quantum gates have the higher fidelities and shorter operation times. The fidelity of our c-phase gate is 98.7% within the operation time of 40.1 ns and that of our cc-phase gate is 94.7% within 60 ns. Moreover, they do not require any drive field.

Universal quantum gates on microwave photons assisted by circuit quantum electrodynamics

  1. Ming Hua,
  2. Ming-Jie Tao,
  3. and Fu-Guo Deng
Based on a microwave-photon quantum processor with multiple superconducting resonators coupled to one three-level superconducting qutrit, we construct the controlled-phase (c-phase)
and controlled-controlled-phase (cc-phase) gates on microwave-photon-resonator qudits, by combination of the photon-number-dependent frequency-shift effect and the resonant operation between the qutrit and a resonator. This distinct feature provides us a useful way for achieving higher fidelity quantum logic gates on resonator qudits in a shorter operation time, compared with others. The fidelity of our c-phase gate can reach 99.51% within 92 ns. The fidelity of our cc-phase gate on three resonator qudits constructed here in the first time, can reach 92.92% within 124.64 ns.

Kerr-Shifted Resonant Quantum Entangling Operation on Qubits in Circuit QED

  1. Ming Hua,
  2. and Fu-Guo Deng
We present a high-fidelity quantum entangling operation on superconducting qubits assisted by a resonator in the quasi-dispersive regime with a new effect — a selective resonance
coming from amplified Kerr-shifted resonator transition frequency. This operation does not require any kind of drive fields, the interaction between qubits, and the non-computational higher-level excitation state, which provides an efficient way to realize quantum computation with superconducting qubits. A universal quantum computation scheme is presented with this operation in a simple way.