Quantum Delayed-choice Experiment Research Articles

The ‘pliable character’ might be the reason for wave-particle duality of light

The delayed-choice experiment is one of the best ways to illustrate the wave-particle duality. The consequences of a quantum delayed-choice experiment have shown that the photon can exhibit dual nature through morphing. There are no hidden variable theories; that can assert the real identities of a photon being a wave and a particle. An open question can emerge, what is the fundamental reason for a photon exposing dual nature. Meanwhile, the recent investigation on photon’s ‘illusive nature’ expounds the apparently unrevealed phenomena like mass posing (zero, real-valued and imaginary rest mass), hidden energy, complex momentum form, and photon possesses this nature for wave-particle duality. The ‘illusive nature’ could interpret why photon does not hold fixed rest mass like another fundamental particles. This article will find out the cause of wave-particle duality from the outcomes of quantum delayed-choice experiments and the ‘illusive nature’ of photons. Furthermore, we will figure out a correlation between dual nature and ‘illusive nature’. Indeed, a photon might manifest dual nature due to its ‘pliable nature’.

Mathematical Relation between Concurrence and Intensity of a Photon in the Quantum Delayed-Choice Experiment

I provide the explicit mathematical expression of the correlation between concurrence and the intensity of a photon in the quantum delayed-choice experiment. This shows us that one may observe the wave-particle duality and entanglement simultaneously.

Simulation of quantum delayed-choice experiment through a single shot

A fundamental feature of micro objects is the wave-particle duality which is addressed by Bohr's complementarity principle. To observe the wave and particle behaviours, quantum delayed-choice experiments based on linear optics have been realized at the single-photon level. Since they were performed by using a single photon as the input, repeating measurements were required in order to obtain different experimental data and adjusting experimental parameters was necessary prior to each of measurements. Different from the previous works, we here realize a simulation of quantum delayed-choice experiment through a single shot, which employs a classical intense light beam as the input instead of a single photon. Experimentally, we demonstrate the trade-off between distinguishability and visibility of photons in a two-arm interferometer in an intuitive way by utilizing the finite beam profile of the light. We observe the morphing between wave and particle natures of photons via a single shot of a charged-coupled-device camera. Since the image is captured within the exposure time which is several milliseconds, the phase fluctuation is negligible, and therefore our experimental setup is robust against the noise. This work provides a simple and new route to inspect quantum duality, which does not require adjusting experimental parameters frequently and only needs performing measurement once.

Modified quantum delayed-choice experiment without quantum control or entanglement assistance

Wheeler's delayed-choice experiment delays the decision to observe either the wave or particle behavior of a photon until after it has entered the interferometer, and the quantum delayed-choice experiment provides the possibility of observing the wave and particle behaviors with a single experimental setup by introducing quantum control. We here propose a modified quantum delayed-choice experiment without quantum control or entanglement assistance, in which a photon can be prepared in a wave-particle superposition state and the morphing behavior of wave-to-particle transition can be observed easily. It is demonstrated that the presented scheme can allow us to rule out classical hidden-variable models in a device-independent manner via violating dimension witness. We also extend the scheme to the situation of two degrees of freedom, first constructing a hybrid quantum delayed-choice experiment which enables a photon respectively exhibits wave and particle behaviors in different degrees of freedom, and then proposing a scheme to prepare the single-photon wave-particle entanglement. This study is not only meaningful to explore the wave-particle complementarity of photons, but also provides potential for the research of the single-particle nonlocality from the perspective of the wave-particle degree of freedom.

A generalized multipath delayed-choice experiment on a large-scale quantum nanophotonic chip

Bohr’s complementarity is one central tenet of quantum physics. The paradoxical wave-particle duality of quantum matters and photons has been tested in Young’s double-slit (double-path) interferometers. The object exclusively exhibits wave and particle nature, depending measurement apparatus that can be delayed chosen to rule out too-naive interpretations of quantum complementarity. All experiments to date have been implemented in the double-path framework, while it is of fundamental interest to study complementarity in multipath interferometric systems. Here, we demonstrate generalized multipath wave-particle duality in a quantum delayed-choice experiment, implemented by large-scale silicon-integrated multipath interferometers. Single-photon displays sophisticated transitions between wave and particle characters, determined by the choice of quantum-controlled generalized Hadamard operations. We characterise particle-nature by multimode which-path information and wave-nature by multipath coherence of interference, and demonstrate the generalisation of Bohr’s multipath duality relation. Our work provides deep insights into multidimensional quantum physics and benchmarks controllability of integrated photonic quantum technology.

The Quantum Delayed Choice Experiment Revisited

The Mach–Zehnder interferometer is a particularly simple device for demonstrating the wave-particle duality. This duality is particularly exhibited in the quantum delayed choice experiment where one realizes a superposition of wave- and particle-like behaviors. Considering this experiment as a generalized measurement described by a positive operator–valued measure (POVM), it realizes a joint measurement of path and interference obeying some duality relations.

Quantum wave–particle superposition in a delayed-choice experiment

Wave–particle duality epitomizes the counterintuitive character of quantum physics. A striking illustration is the quantum delayed-choice experiment, which is based on Wheeler’s classic delayed-choice gedanken experiment, but with the addition of a quantum-controlled device enabling wave-to-particle transitions. Here, we realize a quantum delayed-choice experiment in which we control the wave and the particle states of photons and particularly the phase between them, thus directly establishing the created quantum nature of the wave–particle. We generate three-photon entangled states and inject one photon into a Mach–Zehnder interferometer embedded in a 186-m-long two-photon Hong–Ou–Mandel interferometer. The third photon is sent 141 m away from the interferometers and remotely prepares a two-photon quantum gate according to independent active choices under Einstein locality conditions. We realize transitions between wave and particle states in both classical and quantum scenarios, and therefore tests of the complementarity principle that go fundamentally beyond earlier implementations. The quantum-delayed choice experiment is implemented with multiple entangled photons under Einstein’s locality condition. The wave–particle quantum superposition is realized by controlling the relative phase between the wave and particle states.

Proposal to test quantum wave-particle superposition on massive mechanical resonators

We present and analyze a proposal for a macroscopic quantum delayed-choice experiment with massive mechanical resonators. In our approach, the electronic spin of a single nitrogen-vacancy impurity is employed to control the coherent coupling between the mechanical modes of two carbon nanotubes. We demonstrate that a mechanical phonon can be in a coherent superposition of wave and particle, thus exhibiting both behaviors at the same time. We also discuss the mechanical noise tolerable in our proposal and predict a critical temperature below which the morphing between wave and particle states can be effectively observed in the presence of environment-induced fluctuations. Furthermore, we describe how to amplify single-phonon excitations of the mechanical-resonator superposition states to a macroscopic level, via squeezing the mechanical modes. This approach corresponds to the phase-covariant cloning. Therefore, our proposal can serve as a test of macroscopic quantum superpositions of massive objects even with large excitations. This work, which describes a fundamental test of the limits of quantum mechanics at the macroscopic scale, would have implications for quantum metrology and quantum information processing.

Quantum delayed-choice protocol by means of the polarization degree of freedom of a photon

In this work, we revisit the previously demonstrated experiment called the quantum delayed-choice experiment [Phys. Rev. Lett.107, 230406 (2011)PRLTAO0031-900710.1103/PhysRevLett.107.230406], which shows that it is possible to reveal the wave and particle nature of photons simultaneously. After discussing the main points of this paper concerning the fundamental aspect of wave-particle duality, we demonstrate theoretically that the same observation can be achieved by operating on the polarization state of a photon. For this purpose, we apply the same operators, except that they transform the polarization states, whereas mode operation was performed in the previous work.

Quantum delayed-choice experiment with a single neutral atom.

We present a proposal to implement a quantum delayed-choice (QDC) experiment with a single neutral atom, such as a rubidium or cesium atom. In our proposal, a Ramsey interferometer is adopted to observe the wave-like or particle-like behaviors of a single atom depending on the existence or absence of the second π/2-rotation. A quantum-controlled π/2-rotation on target atom is realized through a Rydberg-Rydberg interaction by another ancilla atom. It shows that a heavy neutral atom can also have a morphing behavior between the particle and the wave. The realization of the QDC experiment with such heavy neutral atoms not only is significant to understand the Bohr's complementarity principle in matter-wave and matter-particle domains but also has great potential on the quantum information process with neutral atoms.

A twofold quantum delayed-choice experiment in a superconducting circuit.

Wave-particle complementarity lies at the heart of quantum mechanics. To illustrate this mysterious feature, Wheeler proposed the delayed-choice experiment, where a quantum system manifests the wave- or particle-like attribute, depending on the experimental arrangement, which is made after the system has entered the interferometer. In recent quantum delayed-choice experiments, these two complementary behaviors were simultaneously observed with a quantum interferometer in a superposition of being closed and open. We suggest and implement a conceptually different quantum delayed-choice experiment by introducing a which-path detector (WPD) that can simultaneously record and neglect the system's path information, but where the interferometer itself is classical. Our experiment is realized with a superconducting circuit, where a cavity acts as the WPD for an interfering qubit. Using this setup, we implement the first twofold delayed-choice experiment, which demonstrates that the system's behavior depends not only on the measuring device's configuration that can be chosen even after the system has been detected but also on whether we a posteriori erase or mark the which-path information, the latter of which cannot be revealed by previous quantum delayed-choice experiments. Our results represent the first demonstration of both counterintuitive features with the same experimental setup, significantly extending the concept of quantum delayed-choice experiment.

Proposal for a quantum delayed-choice experiment with a spin-mechanical setup

We describe an experimentally feasible protocol for performing a variant of the quantum delayed-choice experiment with massive objects. In this scheme, a single nitrogen-vacancy (NV) center in diamond driven by microwave fields is dispersively coupled to a massive mechanical resonator. A double-pulse Ramsey interferometer can be implemented with the spin-mechanical setup, where the second Ramsey microwave pulse drives the spin conditioned on the number states of the resonator. The probability for finding the NV center in definite spin states exhibits interference fringes when the mechanical resonator is prepared in a specific number state. On the other hand, the interference is destroyed if the mechanical resonator stays in some other number states. The wavelike and particlelike behavior of the NV spin can be superposed by preparing the mechanical resonator in a superposition of two distinct number states. Thus a quantum version of Wheeler's delayed-choice experiment could be implemented, allowing of fundamental tests of quantum mechanics on a macroscopic scale.

Quantum Delayed-Choice Experiment with a Beam Splitter in a Quantum Superposition.

A quantum system can behave as a wave or as a particle, depending on the experimental arrangement. When, for example, measuring a photon using a Mach-Zehnder interferometer, the photon acts as a wave if the second beam splitter is inserted, but as a particle if this beam splitter is omitted. The decision of whether or not to insert this beam splitter can be made after the photon has entered the interferometer, as in Wheeler's famous delayed-choice thought experiment. In recent quantum versions of this experiment, this decision is controlled by a quantum ancilla, while the beam splitter is itself still a classical object. Here, we propose and realize a variant of the quantum delayed-choice experiment. We configure a superconducting quantum circuit as a Ramsey interferometer, where the element that acts as the first beam splitter can be put in a quantum superposition of its active and inactive states, as verified by the negative values of its Wigner function. We show that this enables the wave and particle aspects of the system to be observed with a single setup, without involving an ancilla that is not itself a part of the interferometer. We also study the transition of this quantum beam splitter from a quantum to a classical object due to decoherence, as observed by monitoring the interferometer output.

Weak measurement combined with quantum delayed-choice experiment and implementation in optomechanical system

Weak measurement [1,19] combined with quantum delayed-choice experiment that use quantum beam splitter instead of the beam splitter give rise to a surprising amplification effect, i.e., counterintuitive negative amplification effect. We show that this effect is caused by the wave and particle behaviours of the system to be and can't be explained by a semiclassical wave theory, due to the entanglement of the system and the ancilla in quantum beam splitter. The amplification mechanism about wave-particle duality in quantum mechanics lead us to a scheme for implementation of weak measurement in optomechanical system.

Quantum Delayed-Choice Experiment and Wave-Particle Superposition

We propose a simple implementation scheme of quantum delayed-choice experiment in linear optical system without initial entanglement resource. By choosing different detecting devices, one can selectively observe the photon’s different behaviors after the photon has been passed the Mach-Zehnder interferometer. The scheme shows that the photon’s wave behavior and particle behavior can be observed with a single experimental setup by postselection, that is, the photon can show the superposition behavior of wave and particle. Especially, we compare the wave-particle superposition behavior and the wave-particle mixture behavior in detail, and find the quantum interference effect between wave and particle behavior, which may be helpful to reveal the nature of photonessentially.

Is wave-particle objectivity compatible with determinism and locality?

Wave–particle duality, superposition and entanglement are among the most counterintuitive features of quantum theory. Their clash with our classical expectations motivated hidden-variable (HV) theories. With the emergence of quantum technologies, we can test experimentally the predictions of quantum theory versus HV theories and put strong restrictions on their key assumptions. Here, we study an entanglement-assisted version of the quantum delayed-choice experiment and show that the extension of HV to the controlling devices only exacerbates the contradiction. We compare HV theories that satisfy the conditions of objectivity (a property of photons being either particles or waves, but not both), determinism and local independence of hidden variables with quantum mechanics. Any two of the above conditions are compatible with it. The conflict becomes manifest when all three conditions are imposed and persists for any non-zero value of entanglement. We propose an experiment to test our conclusions.

Event-by-event simulation of a quantum delayed-choice experiment

The quantum delayed-choice experiment of Tang et al. (2012) is simulated on the level of individual events without making reference to concepts of quantum theory or without solving a wave equation. The simulation results are in excellent agreement with the quantum theoretical predictions of this experiment. The implication of the work presented in the present paper is that the experiment of Tang et al. can be explained in terms of cause-and-effect processes in an event-by-event manner.

A proposal to implement a quantum delayed choice experiment assisted by cavity QED

We propose a scheme feasible with current technology to implement a quantum delayed-choice experiment in the realm of cavity QED. Our scheme uses two-level atoms interacting on and off resonantly with a single mode of a high Q cavity. At the end of the protocol, the state of the cavity returns to its ground state, allowing new sequential operations. The particle and wave behavior, which are verified in a single experimental setup, are postselected after the atomic states are selectively detected.

Quantum delayed-choice experiment in an environment with arbitrary white noise

The development of quantum technologies depends on the investigation of the behaviour of quantum systems in noisy environments, since complete isolation from its environment is impossible to achieve. In this paper, we show that the main features of a quantum delayed-choice experiment hold even if performed in a system with an arbitrary level of white noise. In light of our results, we analyse recent optical and NMR experiments and show that a loophole on non-locality is not fundamental.

Realization of quantum Wheeler's delayed-choice experiment

Light is believed to exhibit wave–particle duality1 depending on the detecting devices, according to Bohr's complementarity principle2, as has been demonstrated by the ‘delayed-choice experiment’ with classical detecting devices3,4,5,6,7,8,9. A recent proposal10 suggests that the detecting device can also occupy a quantum state, and a quantum version of the delayed-choice experiment can be performed. Here, we experimentally realize the quantum delayed-choice experiment and observe the wave–particle morphing phenomenon of a single photon. We also illustrate, for the first time, the behaviour of the quantum wave–particle superposition state of a single photon. We find that the quantum wave–particle superposition state is distinct from the classical mixture state because of quantum interference between the wave and particle states. Our work reveals the deep relationship between the complementarity principle and the superposition principle, and it may be helpful in furthering understanding of the behaviour of light. Researchers experimentally realize the quantum delayed-choice experiment and show that the quantum wave–particle superposition is clearly different from the classical mixture by comparing interference fringes under various conditions. This work reveals the deep relationship between the complementarity principle and the superposition principle of light.