Proposal for High-Fidelity Quantum Simulation Using a Hybrid Dressed State

Abstract

A fundamental goal of quantum technologies concerns the exploitation of quantum coherent dynamics for the realisation of novel quantum applications such as quantum computing, quantum simulation, and quantum metrology. A key challenge on the way towards these goals remains the protection of quantum coherent dynamics from environmental noise. Here, we propose a concept of hybrid dressed state from a pair of continuously driven systems. It allows sufficiently strong driving fields to suppress the effect of environmental noise, while at the same time being insusceptible to both the amplitude and phase noise in the continuous driving fields. This combination of robust features significantly enhances coherence times under realistic conditions, and at the same time provides new flexibility in Hamiltonian engineering that otherwise is not achievable. We demonstrate theoretically applications of our scheme for noise resistant analog quantum simulation in the well studied physical systems of nitrogen-vacancy centers in diamond and of trapped ions. The scheme may also be exploited for quantum computation and quantum metrology. [11,12] to name just a few. This motivates the considerable effort that is being invested in the creation of the technological basis for these devices with the ultimate goal of constructing quantum devices that can outperform their classical counterparts. One of the main obstacles on this path is the effect of noise and decoherence due to interaction with an uncontrolled environment, the effect of which becomes increasingly severe as the number of system components grows. This poses a considerable challenge for achieving the quantum control of such systems while maintaining the quantum coherence of the system. Hence noise control is central for the future development of scalable quantum technologies.Various theoretical concepts and proposals, e.g. quantum error correction [13,14], decoherence free subspace [15][16][17][18][19][20][21], and dynamical decoupling [22][23][24][25][26][27][28][29][30][31], have been developed for the suppression or avoidance of quantum decoherence. Each of these methods are best suited for specific scenarios. For example, the decoherence free subspace approach is mainly useful in those cases in which noise exhibits a symmetry [21], which however is not always the case. One important example among others that suffer from non-collective noise is the nitrogen-vacancy (NV) center in diamond [32] as a promising physical system for quantum information processing and quantum sensing, the noise of which is dominated by the local nuclear and paramagnetic environment. These noise sources exhibit relatively long memory times and thus can be suppressed using continuous driving. This approach however suffers drawbacks for strong driving where intensity and phase fluctuations may become significant [31]. It is an important observation, that for decoupling fields that are derived from the same source, these fluctuations will be strongly corre-

A dressed spin qubit in silicon

“…The use of the dressed spin states as qubit states provides some interesting advantages for scaled-up quantum computation architectures [11,12]. Two of the four dressed qubit control mechanisms introduced in Section 3 are compatible with scalable architectures based on a global, always-on microwave field and local gate operations [41,8].…”

“…At a donor separation of 50 nm, a coupling strength of up to 400 Hz is achievable, allowing a number of gate operations to be conducted within the coherence time of the dressed qubit, assuming dynamical decoupling. Furthermore, if a pair of quantum systems can be dressed by the same driving field, a hybrid dressed state can be created that is insensitive to both amplitude and phase noise in the continuous driving field [12].…”

“…Because of these benefits, it has been proposed to use dressed states for quantum gates and memories for quantum computing [7,11,12]. In these proposals, the focus was on optically-dressed qubits in trapped atomic ions, because dressing a qubit fundamentally requires a high ratio between the driving field and the intrinsic resonance linewidth, most easily achieved in optics and trapped ions.…”

Entangling distant solid-state spins via thermal phonons

“…To overcome this challenge, here we propose to engineer a decoherence-free subspace (DFS) with suitable driving fields [26] to realize an entangling gate between distant solid-state spins. The logical qubit, which is encoded in the DFS of two quantum systems, becomes much less susceptible to the phonon number of the mechanical oscillator.…”

Estimating the Error of an Analog Quantum Simulator by Additional Measurements

“…Many impressive experiments have been performed recently to examine models from solid-state physics using artificial quantum systems [8][9][10][11] and many additional proposals exist [12][13][14]. Even though the mappings are often more complicated, quantum simulation is also applicable to other fields like particle and astrophysics [15,16].…”